a)€€€€ Write down the symbols for €€€€€€€€€ lithium...

Q1. (a) Write down the symbols for

lithium ................................................................................

fluorine ............................................................................... (2)

(b) The electronic structure of a lithium atom can be shown like this:

In a similar way, complete this diagram to show the electronic structure of a fluorine atom.

(1)

(c) A lithium atom can lose one electron to form a lithium ion which can be written (2)+

A fluorine atom can gain one electron to form a fluoride ion.

Choose from the list the correct way to write the fluoride ion.

(2,6)+ (2,7)+ (2,7)- (2,8)+ (2,8)–

Answer .......................................... (2)

(Total 5 marks)

Q2. (a) The diagrams below show the electronic structure of a magnesium atom and a magnesium ion.

What is the charge on the magnesium ion? ............................................................... (2)

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(b) Calcium bromide has the formula CaBr2.

What does this tell you about the ions in this compound?

....................................................................................................................................

.................................................................................................................................... (2)

(Total 4 marks)

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Atoms of calcium, phosphorus and fluorine are represented below, each with its mass number and proton number.

(a) Use this information to complete the table.

(3)

CALCIUM PHOSPHOROUS FLUORINE

Number of protons in the nucleus 20 9

Number of neutrons in the nucleus 20 16

Number of electrons 15 9

(b) Calcium and fluorine atoms can combine to form the compound calcium fluoride, CaF2.

The fluoride ion is represented by F–.

(i) Explain how the fluorine atom forms a fluoride ion.

..........................................................................................................................

.......................................................................................................................... (2)

(ii) How is the calcium ion represented?

.......................................................................................................................... (2)

(c) Phosphorus and fluorine form a covalent compound, phosphorus trifluoride.

Complete the sentences below which are about this compound.

Phosphorus trifluoride is made up of phosphorus and fluorine ................................

These are joined together by sharing pairs of ............................................... to form

phosphorus trifluoride ........................................................ . (3)

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(d) (i) Sodium chloride, an ionic compound, has a high melting point whereas paraffin wax, a molecular compound, melts easily.

Explain why.

..........................................................................................................................

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.......................................................................................................................... (2)

(ii) Molten ionic compounds conduct electricity but molecular compounds are non-conductors, even when liquid.

Explain why.

..........................................................................................................................

..........................................................................................................................

.......................................................................................................................... (2)

(Total 14 marks)

Q4. (a) The chart shows the reactions of the metal calcium with water, oxygen and dilute hydrochloric acid.

Name (i) solution A .................................................................................................

(ii) solid B .....................................................................................................

(iii) gas C ........................................................................................................ (3)

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(b) The diagrams below show the electronic structure of an atom of calcium and an atom of oxygen.

Describe fully what happens to its electrons when:

(i) a calcium atom forms a calcium ion. State the charge on the calcium ion formed.

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (3)

(ii) an oxygen atom forms an oxygen ion. State the charge on the oxygen ion formed.

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (3)

(c) Calcium oxide is an ionic compound. Why do ionic compounds have high melting points?

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (2)

(Total 11 marks)

Q5. Magnesium oxide is a compound, made up of magnesium ions and oxide ions.

(a) What is the charge on each magnesium ion? ............................................................. (1)

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(b) Explain how the magnesium ions get this charge.

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(Total 3 marks)

Q6. Part of a reactivity series is:

(a) Carbon is used in blast furnaces to obtain iron and zinc from their oxides, but electrolysis has to be used to obtain aluminium from its oxide.

Draw an arrow on the reactivity series above to show where carbon fits into the series. (1)

(b) Predict the method of extraction used to obtain calcium from its ore and explain your answer.

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(c) The formula for zinc oxide is ZnO. Write a balanced equation for the extraction of zinc in the blast furnace.

..................................................................................................................................... (2)

(Total 5 marks)

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Q7. (a) The equation for the reaction that takes place when ammonium chloride is heated is:

NH4Cl(s) NH

3(g) + HCl (g)

ammonium chloride ammonia hydrogen chloride

The diagram shows how a teacher demonstrated this reaction. The demonstration was carried out in a fume cupboard.

(i) Apart from the gases normally in the atmosphere, which two gases would be at X?

..................................................... and ........................................................... (1)

(ii) Name the white solid that has formed at Y.

.......................................................................................................................... (1)

(iii) Why was the demonstration carried out in a fume cupboard?

..........................................................................................................................

.......................................................................................................................... (1)

(iv) Complete the four spaces in the passage.

The chemical formula of ammonia is NH3. This shows that there is one atom of

.......................................... and three atoms of .................................. in each

......................................... of ammonia. These atoms are joined by bonds that

are formed by sharing pairs of electrons. This type of bond is called

a ............................... bond. (4)

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(b) Electrons, neutrons and protons are sub-atomic particles.

(i) Complete the three spaces in the table.

(2)

Name of sub-atomic particle

Relative mass Relative charge

............................... 1 +1

............................... 1 0

...............................

–1

(ii) Which two sub-atomic particles are in the nucleus of an atom?

........................................................... and ............................................... (1)

(Total 10 marks)

Q8. Part of the Periodic Table showing the symbols for the first twenty elements is given below.

(a) Draw diagrams showing the arrangement of electrons (electronic structures) in:

(i) an aluminium atom;

(ii) a chlorine atom.

(2)

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(b) (i) Use electronic structures to help you show why the formula of sodium oxide is Na2O.

(3)

(ii) State why the formation of sodium ions is classified as an oxidation.

..........................................................................................................................

.......................................................................................................................... (1)

(Total 6 marks)

Q9. Ammonium nitrate and ammonium sulphate are used as fertilisers.

(i) Which acid reacts with ammonia to form ammonium nitrate?

.................................................................................................................................... (1)

(ii) Which acid reacts with ammonia to form ammonium sulphate?

.................................................................................................................................... (1)

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(iii) The reactions in (i) and (ii) are both exothermic. How can you tell that a reaction is exothermic?

....................................................................................................................................

.................................................................................................................................... (1)

(iv) The reactions in (i) and (ii) are both examples of acid + base reactions. What is the name of the chemical change which takes place in every acid + base reaction?

.................................................................................................................................... (1)

(Total 4 marks)

Q10. (a) Atoms are made of sub-atomic particles. Complete the six spaces in the table.

(3)



.................................

......................

Neutron ..................... .......................

................................. 1 .......................

(b) Complete the spaces in the sentences.

(i) The atomic number of an atom is the number of ..................................... in its

nucleus and is equal to the number of ..................................................... if the

atom is not charged. (1)

(ii) The mass number of an atom is the total number of ................................. and

...................................... in its nucleus. (1)

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(c) The table gives information about the atoms of three elements.

Two of these elements can react together to form a chemical compound.

Name of element

Chemical symbol

Number of electrons in:

1st

shell 2nd

shell 3rd

shell

Fluorine F 2 7 0

Neon Ne 2 8 0

Sodium Na 2 8 1

(i) What is the name and the formula of this compound?

Name ................................................... Formula .......................................... (2)

(ii) What type of bonding holds this compound together?

........................................................................................................................... (1)

(iii) Explain, in terms of electron transfer, how the bonding occurs in this compound.

...........................................................................................................................

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...........................................................................................................................

........................................................................................................................... (2)

(Total 10 marks)

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Q11. Electrons, neutrons and protons are sub-atomic particles.

(a) Complete the six spaces in the following table.

(3)



....................................... 1 ........................................

....................................... ........................................ 0

.......................................

.........................................

(b) An aluminium atom has 13 electrons. How are these arranged in shells around the nucleus?

.................................................................................................................................... (1)

(c) Chromium atoms have 24 protons and 28 neutrons.

(i) How many electrons does each neutral chromium atom have?

........................................................................................................................... (1)

(ii) What is the mass number of chromium?

........................................................................................................................... (1)

(d) What change occurs to an atom which undergoes the process of reduction in a chemical reaction?

....................................................................................................................................

.................................................................................................................................... (1)

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(e) The diagram shows part of the ionic lattice of a sodium chloride crystal.

Explain why the ions in this lattice stay in place.

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(Total 10 marks)

Q12. (a) A piece of lithium is placed on the surface of some water in a beaker. Hydrogen is given off. Lithium hydroxide is also formed.

Write a word equation for this reaction.

..................................................................................................................................... (2)

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(b) The diagram shows the structure of a molecule of methane.

Write down everything that this diagram tells you about a methane molecule.

To gain full marks in this question you should write your ideas in good English. Put them into a sensible order and use the correct scientific words.

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(Total 6 marks)

Q13. Sodium chloride is an ionic compound.

(Total 2 marks)

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Q14. Use the Data Sheet to help you answer this question.

When sodium reacts with water it forms sodium ions. The diagrams below represent the electron arrangements of some atoms and ions.

Which of the diagrams, A to E, represents the electron arrangement of each of the following?

(i) A sodium atom, Na .............................

(ii) A sodium ion, Na+ ..............................

(Total 2 marks)

Q15. Calcium and magnesium are elements. They are found in the Earth’s crust as compounds, often carbonates and sulphates. Magnesium is also found as its chloride.

(a) Calcium and magnesium are in the same Group in the Periodic Table. State which Group this is.

..................................................................................................................................... (1)

(b) Use the Data Sheet to help you to answer this question.

(i) Write the chemical formula of magnesium chloride.

........................................................................................................................... (1)

(ii) Name the type of bonding in magnesium chloride.

........................................................................................................................... (1)

(Total 3 marks)

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Q16. This question is about sodium chloride (common salt) which is an important chemical.

Sodium chloride can be made by burning sodium in chlorine gas.

(a) Balance the symbol equation for the reaction of sodium with chlorine.

Na(s) + Cl2(g) → NaCl(s)

(1)

(b) (i) Complete the diagrams below to show the electronic structures of a sodium and a chlorine atom. (Atomic number of sodium = 11 and chlorine = 17.)

(3)

(ii) When sodium reacts with chlorine the sodium atoms are changed into sodium ions

(Na+) and the chlorine atoms are changed into chlorine ions (Cl–).

Explain how:

1. a sodium atom changes into a sodium ion;

...........................................................................................................................

........................................................................................................................... (2)

2. a chlorine atom changes into a chloride ion.

...........................................................................................................................

........................................................................................................................... (2)

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(c) The element potassium is in the same group of the Periodic Table as sodium. Potassium reacts with chlorine to make potassium chloride which is sometimes used instead of common salt in cooking.

(i) Predict the formula of potassium chloride.

........................................................................................................................... (1)

By reference to the electronic structures of potassium and sodium explain:

(ii) Why the reaction of potassium with chlorine is similar to the reaction of sodium with chlorine.

...........................................................................................................................

........................................................................................................................... (1)

(d) The electrolysis of sodium chloride solution is an important industrial process. The diagrams below show two experiments set up during an investigation of the electrolysis of sodium chloride.

(i) What would be the reading on the ammeter in experiment 1?

.................................................... A

(ii) Explain your answer.

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (3)

(e) The equations below show the reactions which take place in experiment 2.

H2O(1) → H +(aq) + OH– (aq)

2H+(aq) + 2e– → H2(g)

2Cl–(aq) – 2e– → Cl2(g)

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(i) Which substance provides hydrogen ions?

........................................................................................................................... (1)

(ii) Name the product formed at:

(A) the positive electrode;

...........................................................................................................................

(B) the negative electrode.

........................................................................................................................... (1)

(Total 15 marks)

Q17. Many everyday substances can be classified as acids, bases or salts. For example, car batteries contain sulphuric acid, oven cleaners contain sodium hydroxide and table salt contains sodium chloride.

(a) A solution of each of these substances was tested with universal indicator.

Solution Colour of universal indicator

Sulphuric acid (H2SO

4) red

Sodium hydroxide (NaOH) purple

Sodium chloride (NaCl) green

(i) Explain how these universal indicator colours and the corresponding pH values could be used to identify each of these solutions.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (3)

(ii) Name and give the formula of the ion which causes the solution to be acidic.

Name of ion ..................................................................................................

Formula of ion ................................................................................................. (2)

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(b) Sodium chloride can be made by reacting sodium hydroxide with hydrochloric acid in the presence of an indicator.

(i) What is the name of this type of reaction?

.......................................................................................................................... (1)

(ii) Write a balanced chemical equation for this reaction.

..............(aq) + ..............(aq) → ..............(aq) + ..............(l) (2)

(c) The atomic number for sodium is 11 and for chlorine is 17.

(i) Complete the diagrams to show the electron arrangements for a sodium atom and a chlorine atom.

(2)

(ii) These atoms form different particles by one electron transferring from the sodium atom to the chlorine atom. What is the name given to the particles formed?

........................................................................................................................... (1)

(iii) Why do these sodium and chloride particles bond?

...........................................................................................................................

........................................................................................................................... (1)

(d) Sodium chloride solution is electrolysed to form three products, hydrogen, chlorine and sodium hydroxide.

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Describe how each of these products are formed.

.....................................................................................................................................

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..................................................................................................................................... (3)

(Total 15 marks)

Q18. Ammonia (NH3) is an important chemical which is used to make fertilisers. Ammonia is

made from nitrogen and hydrogen,

(a) The diagrams represent the electron arrangements in atoms of nitrogen and hydrogen.

Complete the diagram showing the arrangement of electrons in a molecule of ammonia.

(1)

(b) Name the type of bonding which holds the nitrogen and hydrogen atoms together in an ammonia molecule.

..................................................................................................................................... (1)

(Total 2 marks)

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Q19. (a) A tin of red kidney beans contains calcium chloride as a firming agent.

Calcium chloride is an ionic compound which contains calcium ions (Ca2+) and chloride

ions (Cl–).

(i) The diagram on the left represents the electronic structure of a chlorine atom.

Complete a similar diagram on the right to represent a chloride ion.

(2)

(ii) Explain how a calcium atom changes into a calcium ion which has a 2+ charge.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (2)

(b) Cola drinks contain phosphoric acid, H3PO

4. The two equations show how phosphoric acid

can be made from phosphorus.

Balance these two equations.

(i) P4 + ........ O

2 → P

4O

10

(1)

(ii) P4O

10 + ................ H

2O → 4H

3PO

4

(1) (Total 6 marks)

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Q20. Hydrogen chloride (HCl) can be made by the reaction of hydrogen (H2) with chlorine (Cl

2).

(a) The diagrams represent molecules of hydrogen and chlorine.

Draw a similar diagram to represent a molecule of hydrogen chloride (HCl). You need show only the outer energy level (shell) electrons.

(1)

(b) The word equation for the reaction of hydrogen with chlorine is shown below.

hydrogen + chlorine → hydrogen chloride

Write a balanced symbol equation for this reaction.

..................................................................................................................................... (2)

(c) Hydrogen chloride gas reacts with magnesium to form the ionic compound called magnesium chloride. Use the table of ions on the Data Sheet to help you to write the formula of magnesium chloride.

..................................................................................................................................... (1)

(d) Why does magnesium chloride have a much higher melting point than hydrogen chloride?

.....................................................................................................................................

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.....................................................................................................................................

..................................................................................................................................... (2)

(Total 6 marks)

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Q21. Toothpastes often contain fluoride ions to help protect teeth from attack by bacteria.

Some toothpastes contain tin(II) fluoride.

This compound has the formula SnF2 .

(a) Calculate the relative formula mass (Mr) of SnF

2.

Relative atomic masses: F = 19; Sn = 119

....................................................................................................................................

....................................................................................................................................

....................................................................................................................................

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Relative formula mass (Mr) = ..........................................

(2)

(b) Calculate the percentage by mass of fluorine in SnF2.

....................................................................................................................................

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Percentage by mass of fluorine = .......................................... % (2)

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(c) A tube of toothpaste contains 1.2 g of SnF2.

Calculate the mass of fluorine in this tube of toothpaste.

....................................................................................................................................

....................................................................................................................................

....................................................................................................................................

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Mass of fluorine = .......................................... g (1)

(d) The diagram represents the electron arrangement of a fluorine atom.

Explain how a fluorine atom can change into a fluoride ion, F–.

....................................................................................................................................

....................................................................................................................................

....................................................................................................................................

.................................................................................................................................... (2)

(Total 7 marks)

Q22. The electrolysis of sodium chloride solution produces useful substances.

(a) Explain the meaning of electrolysis.

.....................................................................................................................................

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..................................................................................................................................... (2)

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(b) The diagram shows an apparatus used for the electrolysis of sodium chloride solution.

Reproduced with the permission of Nelson Thornes Ltd from PATRICK FULLICK et al, ISBN 0-7487-9644- 4. First published in 2006

The electrolysis produces two gases, chlorine and Gas A.

Name Gas A ............................................................................................................... (1)

(c) The electrodes used in this process can be made of graphite. Explain why graphite conducts electricity.

.....................................................................................................................................

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..................................................................................................................................... (2)

(Total 5 marks)

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Q23. Read this passage about metals.

(a) State why metals can be bent and hammered into different shapes.

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..................................................................................................................................... (1)

Metals are crystalline materials. The metal crystals are normally about 20 000 nm (nanometres) in diameter. The atoms inside these crystals are arranged in layers.

A new nanoscience process produces nanocrystalline metals. Nanocrystalline metals are stronger and harder than normal metals.

It is hoped that nanocrystalline metals can be used in hip replacements.

The use of nanocrystalline metals should give people better hip replacements which last longer.

(b) How is the size of the crystals in nanocrystalline metals different from the size of the crystals in normal metals?

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(c) Hip joints are constantly moving when people walk.

Suggest and explain why the hip replacement made of nanocrystalline metal should last longer than one made of normal metals.

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(Total 4 marks)

Q24. This question is about oxygen atoms. The periodic table on the Data Sheet may help you to answer this question.

(a) (i) Oxygen atoms have 8 electrons.

Complete the diagram to represent the arrangement of electrons in an oxygen atom. Use crosses (×) to represent the electrons.

(1)

(ii) Name the part of the oxygen atom that is labelled A on the diagram.

........................................................................................................................... (1)

(b) Two isotopes of oxygen are oxygen-16 and oxygen-18.

16 18

oxygen-16 oxygen-18

O O8 8

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Explain, in terms of particles, how the nucleus of an oxygen-18 atom is different from the nucleus of an oxygen-16 atom.

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(Total 4 marks)

Q25. Read the article and then answer the questions that follow.

Nanotennis!

Tennis balls contain air under pressure, which gives them their bounce. Normal tennis balls are changed at regular intervals during tennis matches because they slowly lose some of the air. This means that a large number of balls are needed for a tennis tournament, using up a lot of materials.

‘Nanocoated’ tennis balls have a ‘nanosize’ layer of butyl rubber. This layer slows down the escape of air so that the ball does not lose its pressure as quickly. The ‘nanocoated’ tennis balls last much longer and do not need to be replaced as often.

(a) How does the ‘nanosize’ layer make the tennis balls last longer?

.....................................................................................................................................

..................................................................................................................................... (1)

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(b) Put a tick ( ) next to the best description of a ‘nanosize’ layer.

(1)

Description ( )

A layer one atom thick.

A layer a few hundred atoms thick.

A layer millions of atoms thick.

(c) Suggest why using ‘nanocoated’ tennis balls would be good for the environment.

.....................................................................................................................................

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.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(Total 4 marks)

Q26. Read the article and then answer the questions.

Nanotennis!

Tennis balls contain air under pressure, which gives them their bounce. Normal tennis balls are changed at regular intervals during tennis matches because they slowly lose some of the air.

‘Nanocoated’ tennis balls have a ‘nanosize’ layer of butyl rubber. This layer slows down the escape of air so that the ball does not lose its pressure as quickly.

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(a) What is the meaning of nanosize?

.....................................................................................................................................

..................................................................................................................................... (1)

(b) Suggest why using ‘nanocoated’ tennis balls would be good for the environment.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(Total 3 marks)

Q27. The following steps show how to use a type of glue.

Step 1 Measure out equal amounts of the liquids from tubes A and B.

Step 2 Mix the liquids to make the glue. Put a thin layer of the glue onto each of the surfaces to be joined.

Step 3 Assemble the pieces to be joined and then hold them together with tape.

Step 4 Leave the glue to set.

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(a) When liquids A and B are mixed a chemical reaction takes place.

(i) This reaction is exothermic.

State how the temperature of the mixture will change as the glue is mixed.

...........................................................................................................................

........................................................................................................................... (1)

(ii) When the glue sets it forms a giant covalent structure.

Explain why substances with giant covalent structures have high melting points.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (2)

(b) The time taken for the glue to set at different temperatures is given in the table below.

Explain, in terms of particles, why increasing the temperature changes the rate of the reaction which causes the glue to set.

.....................................................................................................................................

.....................................................................................................................................

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.....................................................................................................................................

..................................................................................................................................... (2)

(Total 5 marks)

Temperature in °C Time taken for the glue to set

20 3 days

60 6 hours

90 1 hour

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Q28. Read the information in the box and then answer the question.

Aluminium is made by the electrolysis of aluminium oxide.

Aluminium oxide is an ionic compound containing aluminium ions (Al3+) and oxide ions

(O2–).

The diagram below shows the apparatus used to electrolyse aluminium oxide.

(a) In this question you will get marks on using good English, organising information clearly and using specialist terms correctly.

Use information in the box and your knowledge and understanding of this process to answer this question.

Explain, as fully as you can, how aluminium and carbon dioxide are formed in this process.

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(b) Aluminium is a metal.

Explain why aluminium conducts electricity.

........................................................................................................................

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........................................................................................................................ (2)

(Total 8 marks)

Q29. Ammonia has the formula NH3

The diagrams show how electrons are arranged in nitrogen and hydrogen atoms.

(a) Draw a diagram to show how the electrons are arranged in an ammonia molecule.

You need only show the electrons in the highest energy level.

(2)

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(b) Ammonia is a gas at room temperature.

Explain why ammonia has a low boiling point.

........................................................................................................................

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........................................................................................................................

........................................................................................................................ (2)

(c) Ammonia dissolves in water to form a solution with a pH of about 10.

(i) Name the ion in the ammonia solution that causes the pH of 10.

...................................................... ion (1)

(ii) Ammonium nitrate is made by reacting ammonia with an acid.

Name the acid.

...................................................... acid (1)

(d) Instant cold packs are used to treat sports injuries.

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One type of cold pack has a plastic bag with water inside. Inside the bag is a smaller bag containing solid ammonium nitrate.

The outer bag is squeezed so that the inner bag bursts. The pack is shaken and quickly gets cold as the ammonium nitrate dissolves in the water.

Explain why the bag gets cold.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (2)

(Total 8 marks)

Q30. This drinks bottle is made of thermosoftening plastic.

Drinks bottles of this type can be recycled.

Describe and explain how the bottles can be changed into new plastic objects.

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Q31. The picture shows sodium reacting with chlorine.

The reaction forms sodium chloride, which contains sodium ions and chloride ions.

(a) The diagrams show how electrons are arranged in a sodium atom and a chlorine atom.

Explain, in terms of electrons, what happens when sodium reacts with chlorine.

........................................................................................................................

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(b) Explain, as fully as you can, why sodium chloride has a high melting point.

........................................................................................................................

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........................................................................................................................ (3)

(Total 6 marks)

Q32. This barbecue burns propane gas.

The structure of propane is shown below.

(a) Complete the diagram to show how the outer energy level (shell) electrons of hydrogen and carbon are arranged in a molecule of propane.

(1)

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(b) The graph shows how the vapour pressure of propane changes with temperature.

The vapour pressure of a liquid is the pressure of the vapour above the liquid.

(i) Describe, as fully as you can, how the vapour pressure of propane changes with temperature.

...........................................................................................................................

...........................................................................................................................

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...........................................................................................................................

........................................................................................................................... (2)

(ii) The boiling point of a liquid is the temperature at which its vapour pressure is equal to the air pressure above the liquid.

Use the graph to find the boiling point of propane when the air pressure is 100 kilopascals.

Boiling point ................................................... °C (1)

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(c) Explain, in terms of molecules, why propane has a low boiling point.

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..................................................................................................................................... (2)

(Total 6 marks)

Q33. Aspirin tablets have important medical uses.

A student carried out an experiment to make aspirin. The method is given below.

1. Weigh 2.00 g of salicylic acid.

2. Add 4 cm3 of ethanoic anhydride (an excess).

3. Add 5 drops of concentrated sulfuric acid. 4. Warm the mixture for 15 minutes. 5. Add ice cold water to remove the excess ethanoic anhydride. 6. Cool the mixture until a precipitate of aspirin is formed. 7. Collect the precipitate and wash it with cold water. 8. The precipitate of aspirin is dried and weighed.

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(a) The equation for this reaction is shown below.

C7H

6O

3 + C

4H

6O

3 → C

9H

8O

4 + CH

3COOH

salicylic acid aspirin

Calculate the maximum mass of aspirin that could be made from 2.00 g of salicylic acid.

The relative formula mass (Mr) of salicylic acid, C

7H

6O

3, is 138

The relative formula mass (Mr) of aspirin, C

9H

8O

4, is 180

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Maximum mass of aspirin = .............................. g (2)

(b) The student made 1.10 g of aspirin from 2.00 g of salicylic acid.

Calculate the percentage yield of aspirin for this experiment.

(If you did not answer part (a), assume that the maximum mass of aspirin that can be made from 2.00 g of salicylic acid is 2.50 g. This is not the correct answer to part (a).)

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Percentage yield of aspirin = .............................. % (2)

(c) Suggest one possible reason why this method does not give the maximum amount of aspirin.

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(d) Concentrated sulfuric acid is a catalyst in this reaction.

Suggest how the use of a catalyst might reduce costs in the industrial production of aspirin.

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(Total 6 marks)

Q34. This drill contains an electric motor.

The diagram below shows the main parts of an electric motor.

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The carbon contacts are made of graphite. Springs push the contacts against the copper ring. The contacts conduct electricity to the copper ring. The copper ring rotates rapidly but does not stick or become worn because the graphite is soft and slippery.

Graphite has properties which are ideal for making the contacts in an electric motor.

Explain, in terms of structure and bonding, why graphite has these properties.

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Q35. Read the article and then answer the questions that follow.

Hydrogen fuel for cars?

Hydrogen is an excellent fuel. It can be made by the electrolysis of potassium hydroxide solution.

Hydrogen gas can be stored under pressure in a cylinder but a leak of the gas could cause an explosion.

It has been found that lithium nitride can absorb and then release large volumes of hydrogen. A chemical reaction takes place between the hydrogen and the lithium nitride. The hydrogen is held in the resulting compounds by chemical bonds.

The problem is that the rate at which hydrogen is absorbed and then released from normal sized particles of lithium nitride is slow.

Recently scientists have made ‘nanosized’ particles of lithium nitride. These particles absorb hydrogen in the same way as normal sized lithium nitride particles. The ‘nanosized’ particles have the advantage that they absorb and release the hydrogen much faster when needed in the fuel cell.

It is hoped that ‘nanosized’ particles of lithium nitride may provide a safe method of storing hydrogen in the future.

(a) Hydrogen is produced at the negative electrode during the electrolysis of potassium hydroxide solution.

(i) Why are hydrogen ions attracted to the negative electrode?

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(ii) Potassium ions are also attracted to the negative electrode.

Explain why hydrogen gas is formed but not potassium.

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(b) Lithium nitride is made by reacting lithium with nitrogen.

Balance the equation for this reaction.

.......... Li + N2 → .......... Li

3N

(1)

(c) (i) The equation for the reaction of lithium nitride with hydrogen is:

Li3N + 2H

2 LiNH

2 + 2LiH

What feature of this reaction allows the hydrogen to be released?

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(ii) Hydrogen stored in a fuel tank filled with lithium nitride would be safer in an accident than a cylinder full of hydrogen.

Suggest and explain why.

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(d) Lithium nitride is an ionic compound which contains lithium ions (Li+) and nitride ions (N3–).

(i) The formation of a lithium ion from a lithium atom is an oxidation reaction.

Explain why.

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(ii) The diagram shows the electronic structure of a nitrogen atom.

Complete the diagram below to show the electronic structure of a nitride ion (N3–).

(1)

(Total 8 marks)

Q36. Perfumes contain a mixture of chemicals.

The main ingredients of perfumes are a solvent and a mixture of fragrances.

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(a) A sample of the solvent used in one perfume contained 0.60 g of carbon, 0.15 g of hydrogen and 0.40 g of oxygen.

Relative atomic masses: H = l; C = 12; O = 16.

Calculate the empirical (simplest) formula of the solvent.

You must show all of your working to gain full marks for this question.

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(b) Solvent molecules evaporate easily.

Explain why substances made of simple molecules evaporate easily.

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(c) Most companies claim that their perfumes have been tested on skin. A study was made of the tests they used. The study found that each company used different tests.

The perfumes were tested in the companies’ own laboratories and not by independent scientists.

Some companies did not give any information about the tests that they had used.

(i) Suggest why companies test their perfumes on skin.

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(ii) Did the study show that the tests made by the different companies were valid and reliable?

Explain your answer.

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(Total 9 marks)

Q37. (a) Write a balanced symbol equation for the reaction between magnesium (Mg) and oxygen (O

2) to form magnesium oxide (MgO).

..................................................................................................................................... (1)

(b) The diagram shows the electronic structure of a magnesium atom. The atomic (proton) number of magnesium is 12.

Magnesium atom

Draw a similar diagram to show the electronic structure of an oxygen atom. The atomic (proton) number of oxygen is 8.

(1)

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(c) Magnesium ions and oxide ions are formed when magnesium reacts with oxygen.

The diagram shows the electronic structure of an oxide ion.

Oxide ion

Draw a similar diagram to show the electronic structure of a magnesium ion.

(1)

(d) Magnesium oxide is a white solid with a high melting point.

Explain how the ions are held together in solid magnesium oxide.

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(e) Indigestion tablets can be made from magnesium oxide. The magnesium oxide neutralises some of the hydrochloric acid in the stomach.

Complete the word equation for the reaction between magnesium oxide and hydrochloric acid.

hydrochloric acid + magnesium oxide → ...................... + water. (1)

(Total 6 marks)

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Q38. Bricks made from silica (silicon dioxide) are used to line furnaces that operate at high temperatures.

Part of the structure of silica is shown in the diagram.

Suggest and explain why silica is used to make bricks for high-temperature furnaces. In your answer, you should refer to the structure of, and bonding in, silica.

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Q39. Read the article about the use of nanoparticles in sun creams.

Sun creams

Many sun creams use nanoparticles. These sun creams are very good at absorbing radiation, especially ultraviolet radiation. Owing to the particle size, the sun creams spread more easily, cover better and save money because you use less. The new sun creams are also transparent, unlike traditional sun creams which are white. The use of nanoparticles is so successful that they are now used in more than 300 sun cream products.

Some sun creams contain nanoparticles of titanium oxide. Normal-sized particles of titanium oxide are safe to put on the skin.

It is thought that nanoparticles can pass through the skin and travel around the body more easily than normal-sized particles. It is also thought that nanoparticles might be toxic to some types of cell, such as skin, bone, brain and liver cells.

(a) Explain why nanoparticles pass through the skin and travel around the body more easily than normal-sized particles of titanium oxide.

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(b) Explain why sun creams containing nanoparticles should be tested further.

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(c) Suggest why some companies that make sun creams might not want to do more tests.

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(Total 5 marks)

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Q40. Aluminium is a useful metal.

(a) The atomic number (proton number) of aluminium is 13.

Complete the diagram to show the electronic structure of an aluminium atom. Use crosses (x) to represent the electrons.

(1)

(b) Aluminium is used as the electrical conductor for overhead power cables.

Explain why metals are good conductors of electricity.

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(Total 3 marks)

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Q41. The drawing shows a high quality wire used to make electrical connections on a hi-fi system.

(a) Copper is used because it is a very good conductor of electricity. Copper is a typical metal.

(i) Describe the structure and bonding in a metal. You may wish to draw a diagram to help you to answer this question.

To gain full marks in this question you should write your ideas in good English. Put them into a sensible order and use the correct scientific words.

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(ii) Explain, by reference to your answer to part (a)(i), why copper conducts electricity.

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(iii) Explain, by reference to your answer to part (a)(i), why copper can be drawn into wires.

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(b) The copper used to make this wire is “OFC” copper. This stands for ‘oxygen free copper’.

(i) It is thought that when molten copper is cooled and solidified it can take in some oxygen from the air. This may slightly decrease the conductivity of the copper.

Suggest why the conductivity might be decreased.

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(ii) To make it oxygen free, the copper is heated in an atmosphere of hydrogen.

Explain how this will remove the oxygen.

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(Total 8 marks)

Q42. Silicon is an important element used in the electronics industry.

(a) Silicon can be made by heating a mixture of sand (silicon dioxide) with magnesium powder.

The equation for this reaction is shown below.

SiO2 (s)+ 2Mg (s) → 2MgO (s) + Si (s)

Calculate the mass of silicon dioxide needed to make 1 g of silicon.

Relative atomic masses: O = 16; Si = 28

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Mass = ........................................................g (3)

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(b) The resulting mixture of magnesium oxide and silicon is added to a beaker containing hydrochloric acid. The silicon is then filtered from the solution.

(i) The magnesium oxide reacts with the hydrochloric acid and forms magnesium chloride (MgCl

2) solution and water.

magnesium oxide + hydrochloric acid → magnesium chloride solution + water

Write a balanced symbol equation for this reaction, including state symbols.

.......................................................................................................................... (2)

(ii) The gases produced are a mixture of several silicon hydrides.

One of the gases produced in the reaction is the silicon hydride with the formula SiH4.

The structure of this molecule is similar to methane, CH4.

Draw a diagram to show the bonding in a molecule of SiH4. Represent the electrons

as dots and crosses and only show the outer shell (energy level) electrons.

(1)

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(iii) A sample of a different silicon hydride was found to contain 1.4 g of silicon and 0.15 g of hydrogen.

Calculate the formula of this silicon hydride. You must show all your working to gain full marks.

Relative atomic masses: H = 1; Si = 28

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(iv) The silicon hydrides react immediately they come into contact with oxygen in the air. They burst into flames with a small explosion and give out energy.

Which letter, A to H, best describes this reaction?

Letter ................... (1)

Energy involved in breaking and forming bonds

Activation energy

Rate of reaction

Letter

fast A The energy released from forming new bonds is greater than the energy needed

high slow B

to break existing bonds fast C

low

slow D

fast E The energy needed to break existing bonds is greater than the energy released from

high slow F

forming new bonds low fast G

slow H

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(c) The structure of silicon is similar to the structure of diamond.

Describe the structure of silicon and explain why it has a high melting point. You may draw a diagram if this helps.

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(Total 15 marks)

Q43. Millions of years ago the Earth formed as a giant ball of molten rock. The outer surface cooled forming a thin, solid outer crust. Volcanic activity on the surface produced an atmosphere containing the compounds carbon dioxide, ammonia, methane and water vapour.

Describe the bonding in any one of these compounds. You must include electronic structures in your explanation.

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Q44. Uranium metal can be produced by reacting uranium hexafluoride with calcium.

UF6 + 3Ca → 3CaF

2 + U

(a) Describe how calcium and fluorine bond together to form calcium fluoride. The electron arrangement of each atom is shown.

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(b) Uranium has two main isotopes, and . Use these as examples to explain what is meant by the word isotope.

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(c) At the start of a reaction there was 174.5 g of uranium hexafluoride, UF6.

Relative atomic masses: F 19; U 235

(i) Calculate the relative formula mass of uranium hexafluoride, UF6.

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Relative formula mass UF6 = .................................... g

(1)

(ii) Calculate the mass of uranium that would be produced from 134.5 g of uranium hexafluoride.

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Mass of uranium = .................................. g (2)

(Total 12 marks)

Q45. Sodium reacts with chlorine to form the compound sodium chloride.

2Na + Cl2 → 2NaCl

Describe, in terms of electron arrangement, the type of bonding in:

(i) a molecule of chlorine;

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(ii) the compound sodium chloride.

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(Total 7 marks)

Q46. Brine, a solution containing sodium chloride in water, can be used to manufacture chlorine, hydrogen and sodium hydroxide. A student sets up a simplified model of the industrial cell.

(a) The electron arrangements of some atoms are shown here.

H 1

O 2.6

Na 2.8.1

C1 2.8.7

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(i) Use the relevant electron arrangements to describe the bonding in water.

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(ii) Use the relevant electron arrangements to describe the bonding in sodium chloride.

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(b) Use the atomic structures of and to explain the meaning of the term isotopes.

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(Total 8 marks)

Q47. Fluorine is a very useful element. It is placed in group 7 of the Periodic Table.

Use your knowledge of the elements in group 7 to help you answer these questions. You may find that information in the Data Sheet may help you with this question.

(a) Name another element in group 7 of the Periodic Table.

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(b) Cylinders filled with fluorine molecules are commercially available. What would you expect the formula of a fluorine molecule to be?

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(c) Fluoride ions are added to drinking water to help prevent tooth decay. What is the charge on fluoride ions in the water?

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(d) Fluorine reacts with the non-metal sulphur to make sulphur hexafluoride (SF6).

(i) What type of bonding would you expect in sulphur hexafluoride?

.......................................................................................................................... (1)

(ii) Explain the reason for your answer to part (i).

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(Total 5 marks)

Q48. Silicon is an extremely important element. More than a million tonnes of silicon are produced each year. Silicon is made by reducing silicon oxide (sand) with carbon (coke).

(a) (i) Complete the diagram below to show the arrangement of electrons in an atom of silicon. The Data Sheet may help you with this question.

(2)

(ii) Which electrons in the silicon atom take part in chemical reactions with other atoms?

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(iii) What features of all the atoms of the elements in group 4 of the Periodic Table might give them similar chemical properties?

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(b) Silicon is difficult to classify as a metal or a non-metal because it has properties which resemble both. Some of the properties of silicon are listed below.

• Silicon is a shiny blue/grey solid. • Silicon is placed in Group 4 of the Periodic Table. • Silicon has a relative atomic mass of 28. • Silicon has a very high melting point (1410ºC). • Silicon has a very high boiling point (2355ºC). • Silicon conducts electricity. • Silicon oxide will neutralise alkalis. • Silicon forms compounds in which the silicon atoms are bonded to other atoms by

covalent bonds.

(i) Select two properties from the list above in which silicon resembles a metal.

1. .....................................................................................................................

2. ..................................................................................................................... (2)

(ii) Select two properties from the list above in which silicon resembles a non-metal.

1. .....................................................................................................................

2. ..................................................................................................................... (2)

(Total 8 marks)

Q49. The hydrogen halides (hydrogen fluoride, hydrogen chloride, hydrogen bromide and hydrogen iodide) are important chemicals.

The diagram below represents a molecule of hydrogen chloride.

(i) What type of particles are represented by the crosses (X)?

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(ii) What type of chemical bond holds the atoms in this molecule together?

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(iii) Would you expect hydrogen chloride to be a gas, a liquid or a solid, at room temperature and pressure? Explain your answer.

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(Total 5 marks)

Q50. The extract below was taken from a leaflet on the uses of platinum. One of the uses described was in making electrodes for spark plugs in car engines. The spark plug produces the spark which ignites the fuel in the engine.

Spark Plugs

The electrodes in a spark plug have to conduct electricity very well. Since they project into the combustion chamber of the engine, they must also be able to withstand extremely high temperatures in a very corrosive atmosphere.

Nickel-based plugs have been produced for many years. They only last a fairly short time. As the electrodes wear, combustion becomes less efficient and the petrol is not burnt completely.

Platinum and other precious metals can now be used in spark plugs. These last much longer and are more efficient. This can help to reduce air pollution.

The table below gives some information about platinum and nickel.

MELTING

POINT (° C)

BOILING POINT (° C)

POSITION IN REACTIVITY

SERIES

COST (£/kg)

nickel 1455 2920 Higher than gold 2.5

platinum 1769 4107 below gold 6110

(a) Compare nickel and platinum for use in making the electrodes in spark plugs.

A good answer should give advantages and disadvantages of each metal linking these to the properties of the metals. Marks will be given for the way in which you organise your answer.

You will need a sheet of lined paper. (8)

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(b) (i) Describe the structure and bonding in metals.

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(ii) Explain why metals such as nickel and platinum are good conductors of electricity.

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(Total 13 marks)

Q51. (a) The electronic structure of a sodium atom can be written 2,8,1. Write the electronic structure of a potassium atom in the same way.

..................................................................................................................................... (1)

(b) The electronic structure of a sodium atom can also be represented as in the diagram below.

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(i) Draw a similar diagram for a fluorine atom.

(ii) Draw similar diagrams to show the electronic structure of the particles in sodium fluoride.

(4)

(Total 5 marks)

Q52. The following passage was taken from a chemistry textbook.

Germanium is a white, shiny, brittle element. It is used in the electronics industry because it is able to conduct a small amount of electricity.

It is made from germanium oxide obtained from flue dusts of zinc and lead smelters. The impure germanium oxide from the flue dusts is changed into germanium by the process outlined below.

STEP 1 The germanium oxide is reacted with hydrochloric acid to make germanium tetrachloride. This is a volatile liquid in which the germanium and chlorine atoms are joined by covalent bonds.

STEP 2 The germanium tetrachloride is distilled off from the mixture.

STEP 3 The germanium tetrachloride is added to an excess of water to produce germanium oxide and hydrochloric acid.

STEPS 1 to 3 are repeated several times.

STEP 4 The pure germanium oxide is reduced by hydrogen to form germanium.

(a) Balance the equation below which represents the reaction in step 1.

GeO2 + ............ HCl → GeCl

4 + ............ H

2O

(1)

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(b) Write a word equation for the reaction in step 3.

..................................................................................................................................... (1)

(c) Suggest why steps 1 to 3 are repeated several times.

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(d) The equation which represents the reaction in step 4 is shown below.

GeO2 + 2H

2 → Ge + 2H

2O

(i) Explain what is meant by the term ‘reduced’.

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(ii) Calculate the mass of germanium which could be made from 525 g of germanium oxide. (Relative atomic masses: Ge = 73; O = 16).

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Mass ......................................... g (3)

(e) Germanium is difficult to classify as either a metal or a non-metal.

(i) Give as much evidence as you can from the information in this question to support the view that germanium is a metal. Explain your answer as fully as you can.

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(ii) Give as much evidence as you can from the information in this question to support the view that germanium is a non-metal. Explain your answer as fully as you can.

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(Total 13 marks)

Q53. Diesel oil is obtained from crude oil. It can be used as a fuel for car engines. The diagram below represents a compound found in diesel oil.

(a) What is the formula of this compound?

..................................................................................................................................... (1)

(b) Each of the lines on the diagram above represents a covalent bond.

What is a covalent bond?

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(Total 3 marks)

##

Sando-K is a medicine. It is given to people whose bodies contain too little of a particular element.

Sando-K is a mixture of two compounds. The formulae of the two compounds are given below.

KHCO KC1

(a) Which metal do people given Sando-K need?

..................................................................................................................................... (1)

(b) Sando-K contains the ion, CO . Which gas would be produced if a dilute acid was added to Sando-K? (The Data Sheet may help you to answer this question.)

..................................................................................................................................... (1)

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32–

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(c) The compounds in Sando-K contain ions.

Complete the two sentences below.

Atoms change into positive ions by ....................................... one or more

............................................................. .

Atoms change into negative ions by ......................................... one or

more .................................................... . (4)

(d) Electricity can be used to show that an aqueous solution of Sando-K contains ions.

(i) Draw a diagram of an apparatus that you could use to prove that Sando-K contains ions.

(4)

(ii) Explain, as fully as you can, what would happen when the electricity is switched on.

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(Total 13 marks)

Q55. Sulphur hexafluoride is a colourless, odourless, non-flammable gas, which is insoluble in water and extremely unreactive. It is used as an insulator in high voltage transformers and switchgear.

The diagram below represents a molecule of sulphur hexafluoride.

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(a) What type of chemical bond holds the sulphur and fluorine atoms together in sulphur hexafluoride molecules?

..................................................................................................................................... (1)

(b) Explain why sulphur hexafluoride has a low boiling point.

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(c) Explain how three of the properties of sulphur hexafluoride make it suitable for use as an insulator inside electrical transformers.

Property 1: ..................................................................................................................

Explanation: ...............................................................................................................

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Property 2: ..................................................................................................................

Explanation: ...............................................................................................................

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Property 3: ..................................................................................................................

Explanation: ...............................................................................................................

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(Total 6 marks)

Q56. Iron is used (as steel) to make the body panels for cars.

The iron panels have to be bendable so that they can be pressed into the shape required, but must also be strong. The panels must also be able to conduct electricity because they form part of the electrical circuits of the car.

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(a) Iron is a typical metal. Describe the structure and bonding in a metal such as iron. You may use a diagram if you wish.

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(b) Explain how the structure and bonding of iron:

(i) allows the body panels to conduct electricity;

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(ii) allows the body panels to be bent into shape;

........................................................................................................................... (1)

(iii) gives the body panels strength.

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(Total 8 marks)

Q57. The diagram represents the structure of graphite.

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Use your knowledge and understanding of the structure of graphite to explain why graphite can be used:

(a) in the ‘leads’ of pencils;

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(b) as an electrical conductor.

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.................................................................................................................................... (Total 5 marks)

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Q58. The diagram shows a model of part of the giant lattice of a metal.

(a) Name particles X and Y.

X .....................................................

Y ..................................................... (2)

(b) Explain, in terms of the giant structure above, why is it possible to bend a piece of metal.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(Total 4 marks)

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Q59. The diagram shows the structure of diamond.

(a) To gain full marks for this question you should write your ideas in good English. Put them into a sensible order and use the correct scientific words.

Explain, as fully as you can, why diamond has a high melting point.

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.....................................................................................................................................

.....................................................................................................................................

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..................................................................................................................................... (3)

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(b) The diagram below shows the outer electron shells of five carbon atoms in the giant lattice of diamond.

Carbon atom C forms bonds with each of the carbon atoms W, X, Y and Z.

Draw the positions of all the electrons in the outer shells of each of carbon atoms C, W, X, Y and Z.

(3)

(Total 6 marks)

Q60. (i) Complete the drawing to show the electron structure of a hydrogen fluoride molecule. Draw electrons as dots or crosses.

(1)

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(ii) Explain why hydrogen fluoride is a gas at room temperature.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(Total 3 marks)

##

In this question you will need to use the following information:

Relative atomic masses: H 1; O 16; Mg 24.

The volume of one mole of any gas is 24 dm3 at room temperature and atmospheric pressure.

The diagram shows a chemical reaction taking place in a conical flask.

The balanced equation for this reaction is:

Mg(s) + 2HCl(aq) → MgCl2(aq) + H

2(g)

(a) Write a balanced ionic equation for this reaction.

.................................................................................................................................... (2)

(b) Calculate the mass of magnesium required to produce 0.50 g of hydrogen. Show clearly how you work out your final answer and give the unit.

.....................................................................................................................................

.....................................................................................................................................

Mass = ............................... (2)

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(c) (i) Draw a diagram to show how the electrons are arranged in a hydrogen molecule.

(1)

(ii) What is the name of the type of chemical bond between the hydrogen atoms in a hydrogen molecule?

........................................................................................................................... (1)

(d) The chemical formula for hydrogen peroxide is H2O

2.

Calculate, to the nearest whole number, the percentage, by mass, of hydrogen in hydrogen peroxide. Show clearly how you work out your answer.

....................................................................................................................................

....................................................................................................................................

Percentage = ................................. % (2)

(Total 8 marks)

Q62. (a) The diagram shows part of the ionic lattice of a sodium chloride crystal.

of 141

(i) Complete the spaces in the table to give information about both of the ions in this lattice.

(2)

Name of ion Charge

..................................................... .....................................................

..................................................... .....................................................

(ii) When it is solid, sodium chloride will not conduct electricity. However, molten sodium chloride will conduct electricity. Explain this difference.

..........................................................................................................................

..........................................................................................................................

..........................................................................................................................

.......................................................................................................................... (2)

(iii) Complete the sentence.

Sodium chloride conducts electricity when it is molten and when it is

.......................................................................................................................... (1)

(b) The symbol for a calcium atom can be shown like this:

(i) What is the mass number of this atom?

.......................................................................................................................... (1)

(ii) What information is given by the mass number?

..........................................................................................................................

.......................................................................................................................... (1)

(c) Calcium burns in oxygen with a brick-red flame. The product is a white solid. It is calcium oxide and its formula is CaO.

(i) Balance the chemical equation for the reaction.

Ca(s) + O2(g) → CaO(s)

(1)

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(ii) Describe, in terms of electrons, what happens to a calcium atom when it becomes a calcium ion.

..........................................................................................................................

..........................................................................................................................

..........................................................................................................................

.......................................................................................................................... (2)

(Total 10 marks)

Q63. Chlorine will combine with the non-metal element, carbon, to form this molecular compound.

(a) What is the type of bond in this molecule?

..................................................................................................................................... (1)

(b) Explain how these bonds are formed. (You may use a diagram).

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

(2)

(Total 3 marks)

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Q64. (a) By reference to their structure, explain how the particles in a piece of metal are held together and how the shape of the metal can be changed without it breaking.

(You may use a diagram in your answer.)

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

(5)

(b) Explain why metals are good conductors of electricity and suggest why this conductivity increases across the periodic table from sodium to magnesium to aluminium.

.....................................................................................................................................

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.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (4)

(Total 9 marks)

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Q65. Sodium carbonate reacts with acids.

(i) Complete the word equation.

sodium carbonate + hydrochloric acid → sodium chloride + ...................... + water (1)

(ii) Name the salt produced if sodium carbonate reacts with dilute nitric acid.

........................................................................................................................... (1)

(Total 2 marks)

Q66. The questions which follow refer to the element hydrogen.

(a) Draw a diagram to show the bonding in one molecule of hydrogen.

(2)

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(b) The table gives information about two compounds which contain hydrogen.

Use the information in the table to explain why it is difficult to classify hydrogen as a metal or a non metal.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (4)

(Total 6 marks)

Q67. (a) Balance these chemical equations.

(i) H2 + O

2 → H

2O

(1)

(ii) Al + O2 → Al

2O

3

(1)

(b) Briefly explain why an unbalanced chemical equation cannot fully describe a reaction.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

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(c) Explain, as fully as you can, why a water molecule contains two hydrogen atoms but a hydrogen chloride molecule contains only one.

(You may use a diagram in your answer if you wish).

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (3)

(Total 7 marks)

Q68. The diagram shows the elements in Group 4 of the periodic table.

of 141

Carbon is a non-metal and silicon is usually considered to be a non-metal.

Tin and lead have all the usual properties of metals.

Germanium has these properties:

• grey-white shiny solid

• melting point 937°C

• semi-conductor

• reacts with chlorine to form the chloride (GeCl4) which is a liquid

molecular compound

• germanium oxide reacts with acids to form a salt solution and water. It also reacts with alkalis.

(a) With reference to their structure, explain why tin and lead are good conductors of electricity.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (3)

(b) Would you classify germanium as a metal or as a non-metal? Give your reasons.

.....................................................................................................................................

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.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (3)

(Total 6 marks)

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Q69. The diagrams show the giant structures of sodium chloride and diamond.

sodium chloride (melting point 801°C) diamond (melting point 4800°C)

(a) The equation shows how sodium choride could be formed.

Balance the equation.

Na + Cl2

→ Na Cl

(1)

(b) By reference to the detailed structure of sodium chloride explain fully why:

(i) sodium chloride has a quite high melting point,

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (1)

(ii) solid sodium chloride melts when it is heated strongly,

...........................................................................................................................

........................................................................................................................... (2)

(iii) molten sodium chloride will conduct electricity.

...........................................................................................................................

........................................................................................................................... (1)

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(c) By reference to the detailed structure of diamond, explain why the melting point of diamond, is higher than that of sodium chloride.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(Total 7 marks)

Q70. (a) The diagrams represent the atomic structures of two gases, hydrogen and helium.

Hydrogen gas is made up of diatomic molecules (molecules with two atoms). Helium gas exists as single atoms.

(i) How is a molecule of hydrogen formed from two hydrogen atoms? (You may use a diagram as part of your answer)

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (2)

(ii) Why does helium exist only as single atoms?

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (2)

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(b) Hydrogen combines with carbon to form methane. Each molecule contains four hydrogen atoms strongly bonded to a carbon atom.

Explain why methane has a low boiling point.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(Total 6 marks)

Q71. (a) Copper is a metal. Explain how it conducts electricity.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

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(b) Graphite is a non-metal.

Use the information to explain why graphite conducts electricity.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (3)

(Total 5 marks)

of 141

M1. (a) lithium = Li

(ignore mass / atomic numbers) fluorine = F (do not allow if case is incorrect) for 1 mark each

2

(b) (allow ● or o for electrons) (allow any positions for the seven electrons added provided they are on the outer ring)

for 1 mark 1

(c) (2,8)+ or (2,7)–

(brackets not required) gains 1 mark

but (2,8)–

gains 2 marks 2

[5]

M2. (a) positive / + / 2

gains 1 mark

but 2+ / ++ / +2

gains 2 marks 2

(b) Ideas that: 2 Ca2+

Br- [Do not disqualify for "bromine" ions]

Ions / They are in the ratio 1:2 any two for 1 mark each

2 [4]

M3. (a)

for 1 mark each

3

Calcium Phosphorus Fluorine

No of protons 15

No of neutrons 10

No of electrons 20

of 141

(b) (i) gain of electron(s)

from (atoms) (of) calcium for 1 mark

2

(ii) Ca+

gains 1 mark

but superscript only Ca2+ / Ca ++

gains 2 marks 2

(c) atoms electrons molecule(s) not compound

each for 1 mark 3

(d) (i) ideas that

• ionic – strong forces between ions

• molecular – weak forces between molecules each for 1 mark

2

(ii) ideas that

• ionic – ions/charged particles are free to move

• molecular -molecules do not carry a charge each for 1 mark

2 [14]

M4. (a) (i) A calcium hydroxide/limewater/Ca(OH)2 not CaOH

(ii) B calcium oxide/Quicklime/CaO

(iii) C hydrogen/H2 (accept correct formulae)/ not H

2/H

each for 1 mark 3

(b) (i) idea that electrons are lost (by the calcium atom)

gains1 mark

but two electrons are lost (by the calcium atom)/lose outer electrons to get full shell

gains 2 marks

calcium ions are 2+ for 1 mark

of 141

(ii) electrons are gained (by the oxygen atom) gains 1 mark

but two electrons are gained (by the oxygen atom)/gain electrons to get full outer shell

gains 2 marks

oxygen ions are 2– for 1 mark

6

(b) (i)(ii) needs: electron loss/gain number (2) charge (+/–)

(c) idea that they are held together by many/strong forces/bonds a lot of energy/high temperature is required to break these forces/bonds

each for 1 mark 2

[11]

##

(a) positive for 1 mark

1

(b) any reference to loss of electrons for 1 mark

reference to charge being +2 (in (a)) or to loss of 2 electrons (in (b))

for 1 mark 2

[3]

of 141

M6. (a) This part was not marked 1

(b) electrolysis 1

because calcium is more reactive (than aluminium or carbon)

accept it is more reactive or very reactive

1

OR

in a blast furnace 1

because calcium is less reactive (than carbon or lower) 1

(c) any equation from 1 mark for correct formulae 1 mark for balancing

2ZnO + C → 2Zn + CO2

ZnO + CO → Zn + CO2

ZnO + C → Zn + CO 1

[5]

M7. (a) (i) ammonia and hydrogen chloride

both required either order accept formulae if correct in every detail

1

(ii) ammonium chloride / NH4Cl

do not credit ammonia chloride 1

(iii) the fumes / gases / are poisonous / toxic or ammonia and hydrogen chloride are poisonous / toxic / lethal accept just ammonia is poisonous / toxic accept just hydrogen chloride is poisonous / toxic accept vapour is poisonous / toxic do not credit just fumes are dangerous or harmful

1

of 141

(iv) nitrogen do not credit N/N

2

1

hydrogen do not credit H/H

2

1

molecule do not credit compound or mole

1

covalent accept single / molecular

1

(b) (i) proton

neutron

electron either all three correct or one or two correct however do not credit a response which is repeated

2

(ii) protons and neutrons both required in either order

1 [10]

M8. (a) (i) rings of 2, 8 and 3 electrons

credit 2, 8, 3 pay particular attention to the outer shell in diagrams 1

(ii) rings of 2, 8 and 7 electrons credit 2, 8, 7 pay particular attention to the outer shell in diagrams

1

of 141

(b) (i) labels not required on atoms charges need to be shown on ions reference to outer shell is required otherwise a maximum of two marks

structure of atoms/ions marks

(ring of 2, 8, 1 for sodium) or the outer shell of sodium only contains 1 electron

credit 2, 8, 1 or an ion 2, 8 or two circles and 1 electron in outer shell

1

(ring of 2, 6 for oxygen) or outer shell only contains 6 electrons

credit 2, 6 or an ion 2, 8 or two circles 1

transfer of electrons mark

two sodiums needed to supply two outer electrons to oxygen to complete the (one oxygen's) outer shell

award maximum of two marks if a covalent structure is given credit two rings of electrons for sodium showing outer electrons transferring to outer shell of one oxygen for three marks do not accept diagrams showing overlapping rings for third mark

1

(ii) loses an electron credit atoms lose electrons or oxygen takes the electron ignore oil rig

1 [6]

M9. NOTE

In this question and throughout the Paper, if the name of a chemical is asked for, then the formula is acceptable only if it is correct in every detail. If the name is correct and the candidate has tried to be ‘helpful’ by giving, in addition, an incorrect version of the formula, then this is acceptable provided it does not lead to ambiguity.

(i) nitric (acid) accept HN0

3

1

(ii) sulphuric (acid) accept H

2SO

4

1

of 141

(iii) heat given out or temperature rise or energy given out or steam do not credit just ‘use a thermometer’ do not credit just 'change in temperature'

1

(iv) neutralisation accept neutralise accept neutral accept formation of salt or water do not credit exothermic

1 [4]

M10. (a)

both correct in each row

electron ...– (1) allow negative

1

1 .......... 0 allow neutral or none

1

proton .....+ (1) allow positive

1

(b) (i) protons...electrons both correct in correct order

1

(ii) protons....neutrons both correct in either order

1

(c) (i) sodium fluoride do not credit sodium fluorine

1

NaF must be correct in every detail do not credit NAF and the like

1

of 141

(ii) ionic accept ion (bonding) do not credit ironic or iron (bonding)

1

(iii) electron transferred from sodium to fluorine accept electron transferred from metal to non-metal

either positive sodium ion and negative fluoride ion

or correctly identified by the symbols Na+ and F- accept ‘positive sodium ion and negative fluorine ion’

1

or attracted because have opposite charge(s)

or (atoms/ions) form an (ionic) lattice or (atoms/ions) form a crystal e.g.

or both marks may be gained by a suitable dot and cross diagram 1

[10]

M11. (a) proton + (1)

both required

neutron 1 both required

electron – (1) both required

3

(b) 2.8.3 accept words or diagram to this effect

1

(c) (i) 24 1

(ii) 52 1

(d) any one of

• gains one or more electrons accept gains an electron

• becomes an anion do not credit becomes an ion

• becomes a negative ion 1

of 141

(e) sodium ions have a (single) positive charge and chloride ions have a (single) negative charge

do not credit ‘chlorine ions’ but allow this error to be carried forward

1

ions with opposite charge are attracted (to each other)

or the positive ions and the negative ions are attracted (to each other) or the sodium ions and the chloride ions are attracted (to each other)

1

(positive and negative) ions are arranged alternatively (in each direction or dimension)

or ions with the same charge are repelled (by each other) no mark for just ionic bonds

1 [10]

M12. (a) LHS lithium + water

accept Li and H2O

accept hydrogen oxide for water 1

RHS hydrogen + lithium hydroxide accept H

2 and LiOH

ignore attempts at balancing ignore charges

1

(b) Quality of written communication

One mark for the correct use of any three of the terms atom, covalent, bond(ing), saturated, hydrocarbon or alkane

1

of 141

any three from:

one / the carbon (atom) reject molecules once

four hydrogen (atoms) shape / properties neutral

CH4

hydrocarbon

saturated / single bond

covalent bond / shared electrons

alkane reject ionic bond

3 [6]

M13. 8 electrons in outer shell

accept anywhere in outer shell accept dots or crosses

1

negative sign outside bracket 1

[2]

M14. (i) B or 2, 8, 1

for one mark 1

(ii) A or 2, 8

for one mark 1

[2]

M15. (a) Group 2 / Alkaline Earth Metals

for 1 mark 1

of 141

(b) (i) MgCl2/Mg2+ (Cl–)

2

(or equation with correct answer) for 1 mark

1

(ii) ionic / electrovalent for 1 mark

1 [3]

M16. (a) 2 2 multiples of ½ allowed

for 1 mark 1

(b) (i) 2. 8. 1 and 2. 8. 7 gains 3 marks

1 mark for 2 electrons in each inner shell 1 mark for 8 electrons in each second shell 1 mark for 1 electron in sodium outer shell and 7 in chlorine outer shell

3

(ii) sodium atom loses; electron; chlorine atom gains; electron

for 1 mark each

inversion = 2 marks lose negative charge = 1 mark

4

(c) (i) KCl (accept 2KCl) for 1 mark

1

(ii) both have on electron in outer shell/same number of electrons/ lose same number of electrons in compound formation/ both lose one electron

for 1 mark 1

(d) 0 amps; the ions; cannot move in the solid solid Na chloride does not conduct

for 1 mark each 3

(e) (i) water (H2O)

for 1 mark 1

of 141

(ii) (1) chlorine; (2) hydrogen

for 1 mark 1

[15]

M17. (a) (i) H2SO

4 or red (acidic) pH < 7

accept names of compounds accept correct use of acidic

1

NaOH or purple (alkaline) pH > 7

alkaline and neutral without any mention of pH for 1 mark only 1

NaCl or green (neutral) pH 7

ignore high or low pH 1

(ii) hydrogen (ion) accept proton accept hydroxonium ion

1

H+

accept H3O+ for hydroxonium ion

1

(b) (i) neutralisation 1

(ii) NaOH + HCl ignore state symbols

1

NaCl + H2O

ignore state symbols maximum of 1 mark if incorrectly balanced

1

(c) (i) sodium – 2 . 8 . 1 accept 2.8.1 written

1

chlorine – 2 . 8 . 7 accept 2.8.7 written

1

(ii) ion(s) 1

of 141

(iii) attraction between oppositely charged particles (ions) accept attraction between + and – particles (ions) accept electrostatic attraction

1

(d) chloride ions lose electrons to form chlorine

Cl– – e– → Cl 1

hydrogen ions gain electrons to form hydrogen

H+ + e– → H

1

sodium hydroxide remains in solution

Na + and OH– remain in solution to form sodium hydroxide

1 [15]

M18. (a) all electrons correct (inner shell need not be shown)

three bond pairs and two electrons anywhere else can use dots, crosses or e’s in any combination

1

(b) covalent accept phonetic spelling do not accept convalent

1 [2]

M20. (a) bonding pair in the overlap and 6 other electrons arranged around the chlorine

must have either circles or symbols need not be pairs but must not be in the overlap region accept without H and Cl if clear accept all x’s or all o’s

1

of 141

(b) H2 + Cl

2 → 2HCl

accept multiples or fractions accept correct formulae but not balanced for 1 mark correctly balanced equation containing ‘correct’ lower / upper case symbols gets 1 mark

2

(c) MgCl2

accept Mg2+(Cl-)2

1

(d) because magnesium chloride is made of ions or is ionic

accept there are strong forces of attraction between the ions / particles in MgCl

2 or strong electrostatic attractions

accept more energy to separate particles in MgCl2

do not accept MgCl2 molecules

do not accept reference to breaking bonds 1

hydrogen chloride is made of molecules or is covalent

accept there are only weak forces of attraction (between the particles / molecules) in HCl do not accept weak covalent bonds do not accept reference to breaking bonds do not accept MgCl

2 is a solid and HCl is a gas

1 [6]

M21. (a) 157

correct answer with or without working (2 × 19 + 119) for 1 mark only allow (119 + 19 =) 138 for 1 mark only ignore units

2

(b) 24.2 accept answers in the range 24 to 24.2038..... ignore incorrect rounding after correct answer 25 only without working gains 1 mark or 38/157 × 100 gains 1 mark or (19/157 × 100 =) 12 to 12.1 gains 1 mark allow error carried forward from part(a) 38/(a) × 100 gains 2 marks if calculated correctly (19/138 × 100 =) 13.8 gains 1 mark

2

of 141

(c) 0.29 accept answers in the range 0.28 to 0.3 allow error carried forward from part (b) (b)/100 × 1.2 correctly calculated ignore units

1

(d) an electron allow electrons allow electron shared / lost for 1 mark apply list principle for additional particles

1

is gained owtte must be linked to electron accept can hold / take in if in correct context eg it can hold another electron (in its outer shell) = 2 marks it can take an electron (from another atom) = 2 marks ignore reference to fluoride ions incorrect number of electrons gained does not gain the second mark

1 [7]

M22. (a) electric current / electricity 1

plus one from:

• is passed through ionic compound / substance / electrolyte

• passed through molten/aqueous compound / substance must be linked to electricity allow liquid compound / substance do not allow solution / liquid alone

• causing decomposition accept split up / breakdown / breaking up owtte ignore separated accept elements are formed ignore new substances form

1

(b) hydrogen accept H

2

do not accept H / H2

1

of 141

(c) one electron from each atom accept each carbon is bonded to three other carbon atoms leaving one (unbonded) electron owtte

1

is delocalised / free (to move) must be linked to electrons answers of delocalised / free electrons only, gains 1 mark accept each carbon is bonded to three other carbon atoms leaving delocalised / free electrons = 2 marks maximum 1 mark if graphite described as a metal / giant ionic lattice

1 [5]

M23. (a) any one from:

• they are made of layers do not accept line / rows / lattice

• atoms / ions / particles / layers (of atoms) can slide over each other 1

(b) any one from:

• smaller / tiny or very small

do not allow small alone

• correct size range 1 to 100 nanometres

• a few hundred atoms in size if they state smaller and give a size outside range ignore size if it is less than 20,000

1

of 141

(c) harder 1

plus one from:

• so does not wear as quickly / erode as quickly ignore corrode

• less vulnerable to damage owtte harder to wear down = 1 mark

• because they have a high surface area to volume ratio

or

stronger (1)

plus one from: (1)

• less likely to break / do not break accept withstand pressure

• not as vulnerable to damage owtte harder and stronger alone gains 1 mark

• do not bend out of shape

• because they have a high surface area to volume ratio 1

[4]

M24. (a) (i)

or 1

allow any arrangement of electrons on the shells accept o, x, - or e as representing electrons

(ii) nucleus accept nucleus (protons plus neutrons) do not accept protons plus neutrons on its own allow nuclei / nucles / neucleus / phonetic spelling do not accept neutron

1

of 141

(b) it has 2 more neutrons or converse

accept ‘it has more neutrons’ or ‘different number of neutrons’ for 1 mark ‘2 more protons / electrons + correct number of neutrons’ = max 1 mark

or

O-16 has 8 neutrons (1 mark)(*)

O-18 has 10 neutrons (1 mark)(*)

(*)if incorrectly calculated but shows more neutrons in 0-18 allow for 1 mark accept it has more particles or it has 2 more particles for 1 mark ignore any reference to charges just 2 more without reference to particles = 0 marks

2 [4]

M25. (a) Stops / reduces air from escaping (owtte)

allow keeping shape or keeping it hard 1

(b) a layer a few hundred atoms thick 1

(c) any two from:

• last longer

• use fewer balls

• less materials or save resources

• less manufactured accept less factories

• less energy

• less fuel

• less pollution / greenhouse effect / global warming

• less waste ignore references to cost / recycling any two ideas

2 [4]

of 141

M26. (a) 1-100 nm in size

or

a few (hundred) atoms in size accept very / really small / tiny

or 10–9

accept billionth of a metre or any number that implies very small accept measured in nanometers if answer ‘very small’ ignore incorrect numerical values

1

(b) any two from:

• less tennis balls need to be made

• tennis balls last longer or don’t have to replace as often

• less materials / resources / fuel used up / saves resources accept saving materials

• less energy used or making tennis balls uses energy

accept saving energy

• less pollution caused accept named pollutant accept global warming / greenhouse effect

• less waste eg fewer tennis balls going to landfill

2 [3]

M27. (a) (i) increase (owtte) or gets hotter

ignore gives out heat / takes in heat 1

of 141

(ii) any two from:

• bonds are strong accept hard to break

• a lot of energy needed to break bonds allow heat for energy

• all atoms are joined by (covalent bonds accept forms lattice

• a large number of bonds would need to be broken reference to ionic / metallic = 1 mark intermolecular forces /forces between molecules = max 1 mark ignore electrostatic many strong bonds need to be broken = 2 marks accept ‘double bonds’ as equivalent to bonds

2

(b) any two from:

• particles have more energy ignore more vibrations

• particles move faster ignore move more

• particles collide more often or more collisions

accept answers such as hit / bump

• more particles / particle collisions have the activation energy or more of the particles / particle collisions have enough energy to react or collisions are more energetic / harder (owtte) or more of the collisions are successful

if electrons rather than particles stated then max 1 mark there are more collisions and more of the collisions are successful = 2 marks accept more collisions per second / unit of time for 2 marks accept ‘more successful collisions’ for 1 mark

2 [5]

of 141

M28. (a) Marks awarded for this answer will be determined by the Quality of Written Communication (QWC) as well as the standard of the scientific response.

No relevant content. 0 marks

There is a brief description of the electrolysis of aluminium oxide. Level 1 (1–2 marks)

There is some description of the electrolysis of aluminium oxide. Level 2 (3–4 marks)

There is a clear, balanced and detailed description of the electrolysis of aluminium oxide.

Level 3 (5–6 marks)

examples of the chemistry points made in the response

• aluminium oxide is melted / made liquid

• aluminium ions are attracted to the negative electrode

• at the negative electrode aluminium is formed or aluminium ions gain electrons

• oxide ions are attracted to the positive electrode

• oxygen is formed at the positive electrode or oxide ions lose electrons

• the oxygen reacts with carbon to make carbon dioxide or carbon dioxide formed at positive electrode.

(b) there are delocalised electrons / free electrons / electrons which move within the aluminium / metallic structure

1

therefore these electrons are able to carry the current / charge 1

if the candidates use the terms covalent / ionic / molecules / intermolecular incorrectly in the answer this will limit the mark to a maximum of 1.

[8]

M29. (a) one nitrogen atom joined to three hydrogen atoms 1

correct pairs of electrons 1

of 141

(b) because ammonia is made of small molecules / simple molecules / simple molecular structures

1

and so there are weak forces between the molecules or and so the intermolecular forces are weak

1

incomplete answers that link only size of molecule or strength of intermolecular forces with boiling point only gain 1 mark

(c) (i) hydroxide 1

(ii) nitric 1

(d) because this is an endothermic reaction 1

that takes in energy from the surroundings as the ammonium nitrate dissolves

1 [8]

M30. heat 1

then mould / extrude into a new shape / object 1

plastic made of polymer chains that can move (when heated) 1

because plastic / polymer has weak intermolecular forces 1

[4]

M31. (a) the sodium atom loses / transfers an / one electron 1

the chlorine atom gain(s) this / an / one electron 1

involves electrons in the outer energy levels / shells of both the sodium atom and the chlorine atom

1

of 141

(b) sodium chloride has a giant structure / lattice of oppositely charged ions / positive and negative ions

1

the electrostatic forces of attraction / bonds between ions are strong

1

therefore sodium chloride has a high melting point because a large amount of energy is needed to make the ions mobile

1 [6]

M32. (a)

allow all dots or all crosses or combination or all e / e– or – or other suitable symbols centre of symbols must be on or inside overlapping areas within reason

1

(b) (i) any two from:

• no change initially or stays constant at the beginning

• increase

• slowly at first and then more rapidly accept converse arguments

allow vapour pressure is 0 at any temperature <–100oC for 1 mark

accept positive correlation accept explanation based on kinetic theory eg particles have more kinetic energy allow reasonable attempt at using numbers

2

(ii) –44 (using graph) accept –43 to –45 1

of 141

(c) • intermolecular forces / bonds or forces / bonds between molecules 1

• bonds / forces are weak covalent bonds are weak = 0 marks if they do not gain either of the marks on the left then allow simple covalent / molecular / made of small molecules for 1 mark

1 [6]

M33. (a) 2.61 / range 2.5 to 2.7

correct answer with or without or with wrong working gains 2 marks (accept answers between 2.5 and 2.7) if answer incorrect moles of salicylic acid = 2/138 = 0.0145 moles ie 2/138 or 0.0145 gains 1 mark or (180/138) × 2 gains 1 mark or 1 g → 180/138 = (1.304 g) gains 1 mark (not 1.304g alone)

2

(b) 42.1 range 40.7 to 42.3 accept correct answer with or without or with wrong working for 2 marks ecf ie (1.1 / their answer from (a)) × 100 correctly calculated gains 2 marks if answer incorrect percentage yield = 1.1 / 2.61 × 100 gains 1 mark

if they do not have an answer to part (a) or they choose not to use their answer then:

• yield = (1.1 / 2.5) × 100 (1)

• = 44 accept 44 for 2 marks with no working

2

of 141

(c) any one from:

• errors in weighing

• some (of the aspirin) lost do not allow ‘lost as a gas’

• not all of the reactant may have been converted to product eg reaction didn’t go to completion allow loss of some reactants

• the reaction is reversible accept other products / chemicals

• side reactions ignore waste products

• reactants impure

• not heated for long enough

• not hot enough for reaction to take place 1

(d) any one from:

• use lower temperature

• use less fuel / energy ignore references to use of catalyst

• produce product faster or speed up reaction

• more product produced in a given time (owtte)

• increased productivity

• lowers activation energy 1

[6]

of 141

M34. five ideas from the following for one mark each

• each carbon / atom joined / bonded to three other carbon / atoms or each carbon forms 3 bonds

• in layers

• only weak forces (of attraction) / bonds between layers allow weak electrostatic / intermolecular forces /bonds between layers

• layers / atoms can slide over each other

• one electron on each carbon is not used for bonding

• electrons delocalised or electrons free

allow ‘sea’ of electrons

• electrons carry the charge / current

• giant structure / lattice

• covalent (bonds)

• strong bonds or a lot of energy needed to break bonds

reference to ionic bonding = max 4 diagrams could be used: • to show layered structure • to show that each carbon is bonded to three other carbon atoms • to show giant structure (at least 3 rings required)

[5]

M35. (a) (i) any one from:

• they are positive / cations

• they are H+

• opposite charges attract ignore atom

1

(ii) potassium is more reactive (or reverse) assume ‘it’ refers to hydrogen allow potassium reacts with water allow potassium is very reactive or most reactive metal / element allow hydrogen gains electrons more easily / is reduced more easily accept potassium is higher up the reactivity series

1

of 141

(b) 6 and 2

accept correct multiples and fractions 1

(c) (i) the reaction / it is reversible or a description of a reversible reaction

allow ‘it is an equilibrium’ allow reversible symbol drawn correctly allow ‘the reverse / back reaction’

1

(ii) lithium nitride

assume that ‘it’ or if they do not specify means lithium nitride

assume lithium / lithium nitrate refers to lithium nitride

• hydrogen is bonded / held / absorbed / has formed a compound / reacted with lithium nitride

1

plus one of:

• does not explode / cause a fire

• is not free / less hydrogen

• is not under pressure

• does not leak

• is only released slowly 1

• compound of hydrogen with lithium nitride / product is (more) stable / less reactive / less chance of a reaction accept converse for hydrogen as below assume that gas / hydrogen means gas in the cylinder • hydrogen (in cylinder) / gas is not bonded / held absorbed / in a compound / reacted with lithium nitride

1

plus one of: • can explode / cause a fire • is free • is under pressure • can leak • releases quickly

1

(d) (i) loss of an electron or loses electrons

do not accept any ref. to oxygen 1

of 141

(ii) full outer shell of 8 electrons on circle need not be paired can be ×, dot or e do not accept if extra electrons added to inner shell

1 [10]

M36. (a) C H O

0.60 0.15 0.40 1

12 1 16

= 0.05 = 0.15 = 0.025 1

2 6 1 1

C2H

6O

1 mark for dividing the correct amount or multiples of correct amount by A

r

1 mark for proportions 1 mark for whole number ratio – accept any multiple 1 mark for correctly written simplest formula correct formula without working gets only 2 marks correct formula gains full marks provided steps 1 and 2 are correct. ecf can be allowed from step 2 to 3 or step 3 to 4 formula can be in any order eg OH

6C

2

1

(b) intermolecular forces / bonds 1

are weak (covalent) bonds are weak = 0

or

forces between molecules or bonds between molecules (1)

(attractive) forces are weak = 1

are weak (1) if no marks awarded, allow low boiling point or small M

r for 1 mark

1

of 141

(c) (i) to check the safety of the perfume (owtte) accept references to possible harmful / dangerous effects of perfume or possible reactions on skin eg to show it does not damage skin / cause cancer etc. allow to see what it smells like on the skin allow so the company do not have to test on animals

1

(ii) any two from:

idea from text linked with an explanation

• the company claim to have tested the product: but we cannot be certain they have or how thorough they are or how accurately reported

• companies did not disclose how they did their tests: so they could not be checked or so they could not be shown to be reliable / valid or so they could not be repeated

or converse eg companies should disclose how they did their tests so that results can be checked etc.

• companies may not have repeated their tests: so they may not be reliable

• companies do their own tests: so they may be biased or so they may not be truthful about their results or so they may not be reliable or converse eg independent tests should be done so as to ensure there is no bias etc.

• the companies are using different tests: so the results cannot be compared or so results will be different or so results will not be fair / valid / reliable or converse eg companies should do the same tests so that the results will be fair etc.

• companies would not give false information because of damage to reputation or it might lead to litigation

2 [9]

M37. (a) 2Mg + O2 → 2MgO

accept correct multiples / fractions 1

of 141

(b)

electrons do not need to be paired accept dots / circles / e instead of crosses do not allow 2.6 without diagram

1

(c)

electrons do not need to be paired allow without bracket s/ must have the charge accept dots / circles / e instead of crosses ignore extra empty outer shells ignore nucleus

do not allow [2.8]2+ without diagram

1

(d) oppositely charged (ions / atoms) allow positive and negative(ions / atoms)

1

(they) attract must be in correct context accept held by electrostatic forces ignore ionic bonding maximum 1 if they refer to intermolecular forces / attractions / covalent bonds

1

(e) magnesium chloride accept MgCl

2 (if correctly written)

1 [6]

of 141

M38. any four points from:

• high melting point owtte ignore boiling point

• many or all atoms joined together

• each silicon (atom) joined to four oxygen (atoms) or each oxygen joined to two silicon

• covalent (bonds)

• many bonds would need to be broken

• strong bonds allow hard to break bonds

• lot of energy / heat needed to break bonds allow high temperature needed to break bonds

• giant / macromolecular / lattice / diamond structure

• unreactive allow doesn’t react with materials within furnace = 1 mark

• rigid / hard structure

• no free electrons

• poor conductor of heat giant covalent structure = 2 marks max 3 if ionic / metallic bonding mentioned ignore electrostatic ignore molecules / intermolecular forces

[4]

M39. (a) nanoparticles / they are small(er)

accept 1–100 nm or a few atoms in size 1

so can easily pass through pores / skin / cell / membranes / arteries / veins / capillaries / into blood stream owtte

must be a comparative statement can be inferred from smaller particles allow absorbed for pass through

1

of 141

(b) any one from:

• may be toxic (to cells / specific cells) allow may harm / damage / kill cells / organs / tissues or may cause cancer

• to ensure safety or reduce risk or risk of litigation

allow may cause allergies / side effects ignore harmful / dangerous unqualified eg harmful to body / people

• nanoparticles may have different properties

• to see if they pass into the body 1

(c) any two sensible ideas from eg:

• testing is expensive or testing costs money

allow it costs money ignore litigation

• testing is time consuming

• don’t see any reason to test since normal sized particles (of titanium oxide) do not cause harm

accept normal sun cream does not cause harm owtte

• don’t want to risk not producing a popular product (owtte) eg if unsafe will have to stop production or have to remove product if toxic

• testing process / unfavourable results might cause alarm / reduce sales / reduce profit (less money)

• do not want to be seen doing animal testing 2

[5]

M40. (a) 2.8.3 on diagram as Xs / dots

or e

accept paired or unpaired 1

of 141

(b) any two from:

• electrons in highest energy level or electrons in outer shell

• electrons are delocalised or sea of electrons

• electrons are free or electrons move around / flow

• electrons carry charge / current ignore carry electricity

2 [3]

M41. (a) (i) Quality of Written Communication The answer to this question requires ideas in good English in a sensible order with correct use of scientific terms. Quality of written communication should be considered in crediting points in the mark scheme.

maximum 2 marks if ideas not expressed well

layers / lattice / giant structure / regular pattern of atoms (diagram) allow layers / lattice / giant structure / regular pattern of ions do not accept particles

1

outer (shell) electrons accept valence electrons

1

(free to) move (through whole structure) accept delocalised / mobile / free

1

(ii) the free electrons (allow the metal to conduct electricity) accept electrons move / mobile / delocalised

1

(iii) atoms / ions / layers can slide / slip / move over each other 1

(b) (i) copper oxide formed or Cu reacts with oxygen or Cu is oxidised 1

this is a poor conductor or gets in the way of free moving electrons or fewer mobile electrons

do not accept electricity 1

of 141

or

oxygen atoms / oxygen molecules / oxide ions in metal do not accept oxygen pockets / bubbles

prevents / disrupts flow of electrons / current or fewer mobile electrons (1)

do not accept macro explanations do not accept electricity

(ii) hydrogen reacts with oxygen or water is formed or hydrogen reduces copper oxide etc.

1 [8]

M42. (a) Mr (SiO

2) = 60

if Mr incorrect ecf for max 2

1

60 g SiO2 → 28 g Si

correct answer for 3 marks 1

2.14 g SiO2 → 1 g Si

allow 2, 2.1, 2.14 (or anything rounding to 2.14), 2.16 or 2.2 a unit is not required but an incorrect unit loses the third mark

OR Mr (SiO

2) = 60 (1)

moles if silicon needed = = 0.0357

mass of SiO2 needed = 0.0357 × 60 (1)

= 2.14 g (1) allow 2, 2.1, 2.14 (or anything rounding to 2.14), 2.16 or 2.2

OR Mr (SiO

2) = 60 (1)

mass SiO2 = 1 × (1)

= 2.14 g (1) allow 2, 2.1, 2.4 (or anything rounding to 2.14), 2.16 or 2.2

3

(b) (i) MgO(s) + 2HCl(aq) → MgCl2(aq) + H

2O(l)

penalise incorrect symbols correctly balanced equation for 1 mark state symbols for 1 mark allow correct multiples / fractions

2

of 141

(ii)

or

ignore inner shell electrons of silicon allow correct drawings without symbols must clearly indicate four shared pairs of electrons with one electron from each atom

(iii) Si H

1

= 0.05 = 0.15 1

1 3 for whole number ratio can be implied

1

Si H3

accept H3 Si or any correct formula with 1:3 ratio

if in step 1 they get either of ratios incorrect they lose first 2 marks but can be ecf for 3rd and 4th mark evidence of mass / A

r 1 mark

proportions of each 1 mark whole number ratio 1 mark correct formula 1 mark

1

of 141

(iv) C

accept c 1

(c) any four from:

• giant structure / macromolecule / lattice / giant molecule allow giant molecular / giant atomic structure

• each silicon atom joined to four other atoms (or diagram)

• covalent bonds

• bonds are strong or large amount of energy needed to break bonds

accept hard to break bonds

• large number of bonds to be broken mention of giant ionic structure or intermolecular forces or intermolecular bonds max 1 mark diamond or carbon discussion max 3 marks unless clearly linked to silicon

4 [15]

M43. answers apply to:

accept diagrams and/or descriptions

carbon dioxide CO2

ammonia NH3

methane CH4

water H2O

*outer electronic structure of one atom correct or needs correct number of electrons to complete outer shell

1

*outer electronic structure of other atom correct or needs correct number of electrons to complete outer shell

1

*one shared pair of electrons (as one covalent bond)

use of ions or reference to ionic bonding negates this mark 1

*outer electronic structure of compound correct or each atom now has a full outer shell/noble gas electron structure

1 [4]

of 141

M44. (a) calcium atom loses two electrons

accept diagrams with correct labelling 1

(each) fluorine atom gains one electron accept two electrons transfer from a calcium atom to the two fluorine atoms for these first two marks

1

forming full (outer) shells of electrons accept forming full (outer) energy levels or noble gas electronic structures do not accept stable unless qualified

1

giving the ions Ca2+ and F−

1

attraction between ions of opposite charges accept electrostatic attraction between ions if candidate mentions sharing or pairing of electrons then no credit if explanation is entirely correct but they state this is called covalent bonding, the maximum mark is four

1

(b) atoms of the same element 1

atomic number is same accept each contains 92 or same number of protons

1

mass numbers differ or each has a different number of neutrons 1

one has 146 neutrons the other has 143 neutrons accept one has three more or less neutrons than the other

1

(c) (i) 349 1

(ii) 349g UF2 produces 235g U [1]

first mark can be awarded if answer is incorrect

answer = 117.5 1

[12]

M45. (i) can be from diagram chlorine (2.8).7.

accept chlorine needs one more electron 1

of 141

can be from diagram shares a pair of electrons 1

shared pair of electrons is a covalent bond do not accept ionic bond

1

(ii) can be from diagram and appropriately annotated sodium (2.8). 1. and chlorine (2.8).7

1

sodium loses one electron and chlorine gains one electron 1

Na+ and Cl– formed

1

bond formed between oppositely charged ions or ionic bond is formed

do not accept covalent bond 1

[7]

M47. (a) any (must be named) 1

(b) F2

1

(c) –/F–

1

(d) (i) covalent 1

(ii) made of molecules etc. type of bonding when non-metals react.

1 [5]

M48. (a) (i) 14 electrons =

gets 1 mark

2.8.4 = gets 2 marks

2

(ii) outer shell electrons 1

(iii) same number of electrons in outer shell 1

of 141

(b) (1) shiny conducts electricity

(2) oxide neutralises alkalis covalent bonds

4 [8]

M49. (i) electrons 1

for 1 mark

(ii) covalent 1 for 1 mark

(iii) made of small molecules: usually gas or liquid ) dependent on have low melting points ) having first have low boiling points ) point above forces between molecules are weak

any 1 for 1 mark 3

[5]

M50. (a) 8 marks Particularly well structured answer with most points mentioned.

7-6 marks Well structured answer. The two metals will have been compared rather than simply listing advantages/disadvantages. Most of the advantages and disadvantages of each metal have been mentioned.

5-3 marks Some structure to the answer. An attempt to compare the metals by giving some advantages and disadvantages.

2-1 marks Little structure or attempt to compare. Marks gained by listing a few advantages or disadvantages.

Advantages of Nickel: Relatively low cost which makes the sparking plugs cheaper to produce. Quite high melting point which is needed because the temperature in the engine is very high. Good conductor of electricity needed to carry electricity into combustion chamber to produce spark.

Disadvantages of Nickel: Subject to corrosion in engine which means they only last a short time because nickel is higher in reactivity than platinum. Idea that this leads to reduced efficiency, unburnt petrol and air pollution.

of 141

Advantages of Platinum: Less susceptible to corrosion (not corroded) because platinum is very low in reactivity. Idea that this improves efficiency and reduces pollution.- Higher melting point than nickel to withstand the high temperatures in the combustion chamber. Last a lot longer than nickel electrodes due to low reactivity. (Sensible extension here could be longer service intervals etc.)- Good conductor of electricity as for nickel. Extension here could be linked to the idea that the conductivity does not deteriorate as quickly as nickel.)

Disadvantages of Platinum: Cost which will make the sparking plug more expensive. A good candidate might justify cost by longer life, better fuel consumption and less pollution.

8

(b) (i) giant structure/lattice/regular arrangements of atoms any for 1 mark

of atoms/of ions (provided free electrons mentioned) either for 1 mark

delocalised or free electrons for 1 mark

3

(ii) electrons free/can move for 1 mark each

2 [13]

M51. (a) 2, 8, 8, 1

for 1 mark 1

of 141

(b) for 1 mark

Ignore symbol in middle but structure must be drawn NOT 2,7

If covalent; can score mark for changes but not for diagram Arrow showing electron transfer from metal atom to non-metal atom = 2 marks If the ions are not identified then cannot score mark for changes

4 [5]

M52. (a) 4 HCl / 2H2O, allow multiples or fractions if whole equation balances

for 1 mark 1

(b) germanium tetrachloride + water = germanium oxide + hydrochloric acid If symbol equation given it must be correctly balanced Allow germanium

for 1 mark 1

(c) to purify the germanium oxide/remove impurities/give in pure product/to make pure germanium

for 1 mark 1

ensure complete reaction/reaction does not give a good yield

not to increase efficiency/to purify germanium

for 1 mark 1

(d) (i) remove oxygen/addition of hydrogen/gain up electrons allow remove oxygen molecules

(ii) GeO2 = 73 + (2 × 16) = 105

mass of germanium = 525 × (73/105) = 365 g (or alternative methods) apply consequential marking

for 1 mark each 3

of 141

(e) (i) germanium is shiny/lustrous conducts a small amount of electricity * germanium oxide reacts with hydrochloric acid (and) metal oxides react with acid metal oxides are basic metal oxides are reduced by hydrogen Information must be taken from the passage. Apply the list principle if more than three answers are given. Assume the word ‘it’ refers to the metal.

any 3 for 1 mark each 3

(ii) germanium is brittle germanium tetrachloride is a (volatile) liquid made of molecules germanium tetrachloride has covalent bonding or when two non-metals react they have covalent bonding GaC1

4/the salt of germanium undergiven hydrolysis/reacts with water

germanium is not a good conductor of electricity* * conductivity mark can only be given once


[13]

M53. (a) C16

H34

for 1 mark 1

(b) electron gains 1 mark

but shared electrons

gains 2 marks 2

[3]

##

(a) potassium / K for 1 mark

1

(b) carbon dioxide / CO2

for 1 mark 1

(c) losing electrons gaining electrons

for 1 mark each 4

of 141

(d) (i) power supply, (not mains) beaker containing solution, (inert) electrodes and circuit ammeter or bulb/ (or see bubbling etc. at electrodes written by drawing)

for 1 mark each 4

(ii) reading on ammeter/bulb lights / (solution) conducts (electricity) bubbling / gas produced hydrogen produced chlorine / oxygen produced ions move to electrodes (must be linked to ions move) negative ions move to the positive electrode and/or positive ions move to the negative electrode negative ions lose electrons and/or positive ions gain electrons


[13]

##

(a) covalent/description of covalent for 1 mark

1

(b) forces/bonds between the molecules/particles (not atoms) are weak for 1 mark each

2

(c) non-flammable so it will not burn etc. extremely unreactive so it will not react with materials in the transformer, does not conduct electricity so it can insulate the transformer gas so it has freedom to move and insulate whole area

for 1 mark each 3

[6]

of 141

M56. (a) some electrons from outer shells (some electrons) free to move/mobile through whole structure/between atoms/sea of electrons hold atoms together

for 1 mark each

or positive ions in a sea of electrons (owtte) 2 marks

atoms in regular structure/layers giant structure close packed credit diagrams – look for labels

for 1 mark each any 4 4

(b) (i) electrons, free to move (reference to electrons)

for 1 mark each 2

(ii) layers/atoms can slide over each other for 1 mark

1

(iii) free electrons hold atoms strongly together/strong forces of attraction/bonds (between atoms)/tight packing of atoms

for 1 mark 1

[8]

M57. (a) made of layers of carbon atoms weak forces of attraction between layers (owtte) / weak vertical bonds i.e. candidate refers to the diagram layers can slide over each other layers peel off

each for 1 mark

(b) because there are electrons which are free (to move) reason for free electrons / each carbon atom has 3 covalent bonds

each for 1 mark to max 5

[5]

M58. (a) X – (metal) atom / ion 1

Y – electron 1

of 141

(b) free electrons or electrons move 1

(allow metal) atoms / ions to slide over each other

OR

bonding non - directional for 2 marks 1

[4]

M59. (a) Quality of written communication: All scientific words used correctly (covalent, bonds, atoms)

1

any two from

• large numbers of covalent bonds allow giant lattice / structure

• between atoms do not accept between molecules

• (covalent) bonds strong accept need much energy to break

2

of 141

(b)

each carbon has 4 electrons 1

one shared pair 1

four shared pairs 1

[6]

M60. (i) 1

of 141

(ii) weak forces accept weak bonds

1

between molecules / intermolecular reject intramolecular

1 [3]

M61. (a) Mg + 2H+ → Mg2+ + H2

* reactants correct in every detail * products correct in every detail

if the spectator ions are sown then (1) mark should be credited but only if they are shown correctly on both sides e.g. Mg + 2H+ + 2CI- → Mg2+ + 2CI- + H

2

2

(b) 24 (parts) of magnesium → 2 (parts) 1

of hydrogen or equally clear working (so) 6 grams/g (are needed) 1

unit required

(c) (i) two (and no more) atoms shown to be sharing their single electrons examples

do not credit if anything which contradicts the impression that these are hydrogen atoms

1

(ii) (single) covalent (bond) 1

(d) (×100) = 6 (just 6 is worth (1) mark) 1

× 100 = 6 or similar is (0)

do not credit 5.8823529 and the like

1 [8]

of 141

M62. (a) (i) sodium........ positive or +

both required 1

chloride... negative or –

both required do not credit chlorine

1

(ii) ions not free (to move) in solid crystal / lattice

ions are free to move when sodium chloride is molten 1

or ions are mobile

do not credit when ions are molten allow 'particles' for ions (1) mark do not credit electrons etc

1

(iii) dissolved in water or in aqueous solution accept in solution accept in water or when a gas/ vapour or solid it will not

1

(b) (i) 40 1

(ii) (total) number of protons and neutrons (in the nucleus) 1

(c) (i) 2Ca + O2 -+ 2CaO

accept any 2n : n : 2n ratio do not credit if any other change has been made

1

(ii) any two from

electron(s) is / are lost

from the outer shell / orbit / ring or from the shell furthest the nucleus or from the 4th shell

two / both (electrons are lost) accept two electrons are lost for (2)marks accept both electrons are lost from the atom for (1) mark

2 [10]

of 141

##

(a) covalent bonds for 1 mark

1

(b) any reference to shared electrons gains 1 mark

but idea that bond is shared pair of electrons

gains 2 marks 2

[3]

##

(a) Idea that the electrons do not belong to specific atoms/delocalised electrons [credit if done on appropriate diagram] metal atoms form positive ions the attraction which exists between particles with opposite charges, holds the metal together no specific bonds exist between adjacent atoms/ions atoms/ions can slide over each other so allowing metals to bend

each for 1 mark 5

(b) some electrons in the structure are delocalised/free to move for 1 mark

these free electrons carry the electric current for 1 mark

from left to right across the period, atoms of elements have more free electrons

gains 1 mark

but from left to right across the period, atoms of elements have more free electrons because they have more electrons in the outer shells

gains 2 marks 4

[9]

M65. (i) carbon dioxide (allow CO2)

for 1 mark 1

(ii) sodium nitrate (accept correct formula) for 1 mark

1 [2]

of 141

M66. (a) correct representation of 1 atom of hydrogen e.g.

gains 1 mark

but correct representation of 1 molecule of hydrogen e.g. or H-H

gains 2 marks

2

(b) idea that: hydrogen/metals form positive ions/lose electrons

gains 1 mark

but hydrogen and the metals form positive ions/lose electrons

gains 2 marks

hydrogen/non-metals form covalent bonds/share electrons gains 1 mark

but hydrogen and the non-metals form covalent bonds/share electrons

gains 2 marks 4

[6]

M67. (a) (i) 2 H2 + O

2 → 2 H

2O (allow H

2 + ½O

2 → H

2O)

both circled for 1 mark 1

(ii) 4 A1 + 3 O2 → 2 A1

2O

3

all circled for 1 mark 1

(b) idea that: must end up with the same number of atoms otherwise matter is shown to be lost/gained doesn’t show correct amount of each element/compared

each for 1 mark 2

of 141

(c) idea that: oxygen has 2 electrons short in outer shell ) in words or chlorine has 1 electron short in outer shell ) indicated on diagram (shared pair/covalent bond with) hydrogen atom supplies one further electron* *(but do not allow hydrogen gives away electron or ionic bond)

for 1 mark each 3

[7]

##

(a) idea that some of the outer electrons of the atoms are free to move can move anywhere across the (giant) structure the flow of electricity is a stream of electrons

each for 1 mark

or electrons carry a (negative electrical) charge 3

(b) metal element [shiny] appearance

[high] melting point forms an oxide that reacts with acids to make a salt

1 of these for 1 mark

non metal element forms an oxide that reacts with alkalis

with chlorine forms a molecular chloride 1 of these for 1 mark

semi-conductor suggests in between this, or any other for 1further mark

[NB Maximum of 2 for arguing metal/non-metal only] Under each head 1 wrong reason → maximum of 1 available 2 wrong reasons → no mark available]

3 [6]

M69. (a) 2 Na + Cl2 → 2 NaCl

allow 2 Na+ Cl– for 1 mark

(allow Na + ½Cl2 → Na Cl) 1

of 141

(b) (i) idea that

• it has strong (attractive) forces/bonds between ions / charged particles for 1 mark

(not ‘..it has a rigid structure’- this defines a solid or ‘...particles close together’ – they are in a liquid)

1

(ii) ideas that

• there is increased vibration of ions / particles on heating

• ions have sufficient energy to overcome attractive forces / to break out of the

• rigid structure / to move about

(must be in terms of increased energy of particles lions) each for 1 mark

2

(iii) • ions can go to electrodes / ions are free to move for 1 mark [do not credit ‘ions carry charges’]

1

(c) ideas that

• it has stronger attractive forces between atoms/particles (not ‘ions’)

• each carbon atom forms covalent bonds with neighbouring atoms each for 1 mark

2 [7]

M70. (a) (i) idea that

• two hydrogen atoms share one pair of electrons

• linked by a covalent bond

• each then has two outer electrons / a full outer shell / two

• electrons in the highest (occupied) energy level

(2 marks may be awarded for a correct electron diagram i.e. with electrons on boundary of or within marked area).

any two for 1 mark each 2

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(ii) idea that

• helium atoms do not give / take / share electrons / react

• because the (outer) shell / orbit is full

or

• highest (occupied) energy level is full

(but not just “contains two electrons”) for 1 mark each

2

(b) idea that

• the (attractive) forces between molecules are weak

(not bonds between atoms)

• so little energy is required / it is easy for molecules to escape from the liquid* / escape from other molecules*

(allow evaporate / change into a gas) for 1 mark each

2 [6]

M71. (a) idea that

• copper has free electrons / electrons that move throughout the structure

gains 1 mark

but

• in copper, electrons from the highest (occupied) energy level /outer shell, are free / can move throughout the structure

gains 2 marks 2

of 141

(b) idea that

• in graphite, only three bonds are formed by each carbon atom for 1 mark

• one outer electron (per atom), free to move for 1 mark

• an electric current is a flow of (free) electrons* for 1 mark

(* this mark to be given in either (a) or (b) but not in both) 3

[5]

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a)€€€€ Write down the symbols for €€€€€€€€€ lithium...

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