Studying Matter and Its Changes

An Introduction to Chemistry

1. Chemistry: the study of matter and its composition. Chemistry is also the study of what

happens when matter interacts with other matter.

2. Matter: anything that has mass and volume (takes up space), and can be either solid, liquid,

or gas.

3. Properties: characteristics that help you describe and identify matter. An example of

properties includes physical state, color, odour, texture, boiling temperature, density, and

flammability (combustibility).

4. Physical Property: a property that you can observe without changing one kind of matter into

something new (words).

5. Chemical Property: a property that you can observe when one kind of matter is converted

into a different kind of matter.

6. Qualitative: described with words.

7. Quantitative: described with numbers.

8. Physical Change: changes that affect the physical appearance of matter, but not its

composition.

9. Melting (Fusion): the change from a solid to a liquid.

10. Freezing: the change from a liquid to a solid.

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11. Vaporization/Condensation: the change from a gas to a liquid

12. Sublimation: the word used to describe both the change from a gas directly to a solid, and

the change from a solid directly to a gas.


An Introduction to Chemistry Continued…

11. Vaporization/Condensation: the change from a gas to a liquid

12. Sublimation: the word used to describe both the change from a gas directly to a solid, and

the change from a solid directly to a gas.

13. Mixture: a physical combination of two or more kinds of matter.

14. Pure Substance: has a definite composition, which stays the same in response to physical

changes.

15. Element: a pure substance that cannot be separated chemically into any simpler

substances.

16. Compound: a pure substance that results when two or more elements combine chemically

to form a different substance.

17. Atom: the smallest particle of an element that still retains the identity of the element.

18. Proton/Neutron: a cluster that forms the central core, or nucleus of an atom. Protons have

a positive charge, while Neutrons have a neutral charge.

19. Electrons: fast moving objects that occupy the space that surrounds the nucleus of an

atom.

20. Atomic Mass Unit: used to compare the mass of subatomic particles.

21. Atomic Number: refers to the number of protons in the nucleus of each atom of an element.

22. Mass Number: the total number of protons and neutrons in the nucleus of one of its atoms.

23. Atomic Symbol: each element has a different atomic symbol, and all chemists around the

world use the same atomic symbol.


24. Periodic Table: the arrangement of elements into rows (periods) and columns (groups)

according to their similar properties.

An Introduction to Chemistry Continued…

25. Groups (columns): elements with similar properties that are arranged in a vertical (up and

down) column in the periodic table.

26. Periods (rows): the horizontal (left to right) rows in which the elements are placed in the

periodic table.

27. Metals: are good conductors of heat and electricity, solid at room temp, form positive ions

(cations), and are to the left of the “staircase” on the periodic table.

28. Non-metals: are poor conductors of heat and electricity, can be solid, liquid, or gas at room

temperature, form negative ions (anions), and are to the right of the “staircase” on the periodic

table.

29. Metalloids: have properties of both metals and non-metals, and may or may not form ions.

30. Noble Gas: any of the inert and non-inert gaseous elements of the helium group in the

periodic table.

31. Valence Electrons: an electron that occupies the outermost energy level, or shell, of an

atom.

32. Halogen: any of the five non-metals in the periodic table. Found in group 17 – the Halogen

family.

33. Transition Metals: elements that are in the d-block of the period table (groups 3-12).


Energy Level Diagrams

Recall: the number of protons in the nucleus of an atom is equal to the atomic number

of the element, and, the number of electrons around the nucleus of an atom is equal to the

number of protons.

An energy level represents the specific value of energy of an electron and corresponds to a

general location. The number of occupied energy levels in any atom is normally the same as the

period number in which the atom appears.

For the first three energy levels, the maximum number of electrons that can be present are 2, 8,

and 8, in order of increasing energy.

A lower energy level is filled with electrons to its maximum before the next level is started.

The electrons in the highest energy level that contains any electrons are valence electrons. For

the representative elements (1, 2, 12-18) the number of valence electrons is the same as the

last digit of the group number of the atom. For example: Br is in Group 17, so it has 7 valence

electrons.

The markings that are found above are the symbols that are used when marking an energy level

diagram. The symbol on the left is the first one you use, and the symbol on the right is the

second one that you use. The symbols must be used in this order, if they are not, then

technically the energy level diagram is wrong.


When working on an energy level diagram, the above chart must be used. You begin with 1s,

and continue until you have the element's energy level diagram finished. When you start from

1s, you must continue on to 2s, 2p, 3s, 3p, and so on. Remember that, S holds 2 symbols, P

holds 6 symbols, D holds 10 symbols, and F holds 14 symbols.


Ionic Configurations

1. Monatomic Ion: single atoms that have gained or lost electron(s).

2. Cations: positively charged ions. They are formed from metallic elements when they lose

electron(s).

3. Anions: negatively charged ions. They are formed from non-metals when they gain

electron(s).

The Octet Rule:When atoms combine, bonds form so that each atom ends up with an octet (8) of valence

electrons. Only electrons are affected.

Lost 1 (1+) – 3 2

You are losing 1 electron, therefore your negative charge decreases, while your positive charge

is increasing.

Gained 2 (-2) – 33 36

You are gaining electrons, which are negative; therefore you are increasing your negative

charge, and losing some positive charge.


Diatomic Molecules

Diatomic Molecules are elements that exist as polyatomic molecules. These include: H2, N2,

O2, F2, Cl2, Br2, and I2.

HOBrFINClH for Hydrogen

O for Oxygen

Br for Bromine

F for Fluorine

I for Iodine

N for Nitrogen

Cl for Chlorine


Binary Compounds

Binary compounds are compounds composed of two elements. For example: Sodium Chloride

(NaCl) is a binary compound. The second element always has the suffix "-ide" attached to the

end of the word. If you were given MgO, the element's name would be Magnesium Oxide --

notice the "-ide" suffix that has been attached to Oxygen.

Things to Remember: Remember never to add “-ide” to the end of the first element.


Binary Molecular Compounds

Binary molecular compounds are caused when the atoms of two different elements group together as molecules. The two elements in binary molecular compounds are usually two non-metals.

Writing Binary Molecular Compounds:

1. The first Element in the name of the formula is usually the one that is farthest to the left on the periodic table.

Example: In a compound containing carbon and oxygen, the carbon is named first because carbon is to the left of oxygen.

2. The suffix "-ide" is attached to the name of the second element

Example: In a compound containing carbon and oxygen, the name "oxygen" is changed to "oxide".

3. Use prefixes to indicate how many atoms of each type are present in one molecule of the compound. Note that the prefix "mono" is used only for the second element. Drop the "o" if the second element is oxygen. (Example: Monoxide, not Monooxide)

Example: A compound consisting of molecules with one carbon atom and two oxygen atoms, CO2, is called Carbon Dioxide. A compound consisting of molecules with one carbon and one oxygen, CO, is Carbon Monoxide.

Prefixes for Binary Molecular Compounds

Mono 1 Octa 8

Di 2 Nona 9

Tri 3 Deca 10

Tetra 4

Penta 5

Hexa 6

Hepta 7

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Binary Ionic Compounds

The first element in the name is the metal. For example: use the name Sodium to name the

metal NaCl. Use the name Calcium to name the metal CaCl2. The second element, which is the

non-metal, is named as an ion. In other words: the suffix "-ide" is attached to the name. For

example: NaCl is called Sodium Chloride. This allows us to name the non-metal NaCl. Be sure

to put the parts of the name together. For example: NaCl is called Sodium Chloride, and CaCl2

is called Calcium Chloride. Remember names of ionic compounds do not use the prefixes such

as mono, di, tri, and so on, and if the numbers on each element are not equal, that is, if they are

+2 and -3, or +1 and -2 (simply as an example), take them for a “walk”. They will switch sides,

and for instance: Be+2 N-3 becomes Be3N2, while Na+1 S-2 becomes Na2S.

Writing Formulas for Binary Ionic Compounds:

1. Write the unbalanced formula, placing the metal ion first.

Example: Magnesium Fluoride

Mg = Magnesium and F = Fluorine, therefore: MgF

2. Write the charge of the ion on the top of the appropriate symbol. Recall that metal ions from

Group 1 have a charge of +1. Metal Ions from Group 2 have a charge of 2+. Halogen ions have

a charge of -1. Oxide ions have a charge of -2.


Mg2+ and F-1

3. Cross over the numerical value of each charge and write this number as the subscript for the

other ion in the compound. Do not include negative or positive signs, and do not include the

subscript #1 in the formula.


Mg+2 and F-1, therefore: MgF2

You give the 2 to the F and the -1 to the Mg, but you do not write "-1 or 1" because there is an

understanding that when an element is written as such, the 1 is present (just not visibly written).


Transition Metals

Transition metals form ions that have multiple charges. Some metals form two different ions,

and you must use a roman numeral after the metal to distinguish the charge.

Example: Iron (III) Oxide

Fe+3 and O-2, therefore: Fe2O3

You should know that the transition metal has a charge of positive 3, and you should have

already known, from past knowledge, that Oxide, or Oxygen, has a charge of negative 2, so,

Fe+3 and O-2. Now you must take the numbers for a “walk”. Fe+3 O-2 becomes Fe2O3.

Remember that the first element is always a positive!

Example: Tin (IV) Iodide

Sn+4 and I-1, therefore: SnI4

Roman Numerals

I 1

II 2

III 3

IV 4

V 5

VI 6

VII 7

VIII 8

IX 9

X 10


Polyatomic Ions

Polyatomic ions are the groups of ions that collectively carry a charge because of an excess or

deficiency of electrons. Negatively charged polyatomic ions generally end in "-ate" or "-ite". If

more than one polyatomic ion is bonded to another ion, the polyatomic ion must be put in

brackets.

Example: Magnesium Nitrate

Mg+2 and NO3-1, therefore: Mg(NO3)2

The Polyatomic Ion, which is Nitrate, has a charge of negative 1, while Magnesium has a charge

of positive 2. You must take these numbers for a “walk”, but because you are working with a

polyatomic ion, you must cover the polyatomic ion with brackets, because MgNo32 would simply

be the wrong answer.

Example: Sodium Acetate

Na+1 and CH3COO-1, therefore: NaCH3COO

The Polyatomic Ion, which is Acetate (CH3COO), has a charge of negative 1, while Sodium has

a charge of positive 1. These numbers are both 1s, so when you take them for a “walk” you are

left with a final answer of NaCH3COO, and there is no need for a brackets around the

polyatomic ion because Na is a +1; however if Sodium were replaced with Calcium, which has a

charge of positive 2, the answer would end up being Ca(CH3COO)2.

Example: Copper (II) Sulfate

Cu+2 and SO4-2, therefore: CuSO4

The Polyatomic Ion, which is Sulfate (SO4), has a charge of negative 2. You are working with a

Transition Metal and a Polyatomic Ion, but you do not work any differently. You are given the

charge of the Transition Metal, which is Copper (positive 2). You take these numbers for a

“walk” and obtain a final answer of CuSO4, because both numbers cancel each other out (2 - 2

= 0).


Naming and Writing Acids

Acids are compounds that contain hydrogen, and they are dissolved in water -- aqueous (aq).

Binary Acids consists of 2 elements and the first is always hydrogen. The second element will

always be a non-metal and the suffix will always be "-ic".

Example:

HF = Hydrofluoric Acid

HCl = Hydrochloric Acid

HBr = Hydrobromic Acid

H2S = Hydrosulfic Acid

Oxygen containing acids contain 2 ions. The first element will always be hydrogen. The second

element will always be a polyatomic ion that contains oxygen. The name is formed by dropping

the word "hydrogen" as well as the suffix from the second element. The suffix is replaced with a

new one plus the word acid. A polyatomic ion on that ends with "-ite" will become "-ous", and a

polyatomic ion that ends with "-ate" becomes "-ic".

Example:

H3BO3 = Boric Acid (You have hydrogen and a polyatomic ion. You drop the "Hydro-" suffix,

and change "-ate" to "-ic", because Boric is actually the polyatomic ion "Borate").

HNO3 = Nitric Acid

H2CO3 = Carbonic Acid


Writing and Balancing Equations

An unbalanced equation can be seen below:

Na + Cl2 NaCl

Reactant(s) Product

When Sodium is added to Chlorine, the result is Sodium Chloride. Remember that you must add

the “-ide” prefix to the end of the second element, because one is a metal (Sodium – NA), and

the second is a nonmetal (Chlorine – Cl2).

Balancing the unbalanced equation:

Na + Cl2 NaCl

Reactant(s) Product

2Na + Cl2 2NaCl

The Steps to Writing and Balancing a Chemical Equation:

1. Write out the unbalanced equation. Ensure that you have copied all of the chemical formulas

correctly.

2. Begin with the most complex substance – the substance with the largest number or greatest

variety of atoms. Balance the atoms that occur in the largest numbers. Leave your HO’s

(Hydrogen and Oxygen), and all other elements that occur in smaller numbers until later.

3. Balance any polyatomic ions that occur on both sides of the equation as one unit, rather than

as separate atoms.

4. Balance any Hydrogen or Oxygen atoms that occur in a combined or uncombined state.

5. Balance any other element that occurs in its uncombined state.


6. Check your answer by counting the number of atoms on each element on each side of the

equation.


Questions for Writing and Balancing Equations

1. Copper (II) nitrate reacts with Potassium hydroxide to form Potassium nitrate and solid

Copper (II) hydroxide. Balance the equation.

Copper: Cu+2 and Nitrate: NO3

-1 Cu(NO3)

2

Potassium: K+1 and Hydroxide: OH-1 KOH

Now that the chemical formulas have been corrected, you can continue with the balancing.

Cu(NO3)

2 + KOH KNO

3 + Cu(OH)

2

Cu(NO3)

2 + 2KOH 2KNO

3 + Cu(OH)

2

Remember to “walk” your numbers if it is necessary.


Classifying Chemical Reactions

Identifying types of chemical reactions helps chemists to predict what will happen when two

substances interact. Most chemical reactions can be classified as one of four main types of

reactions. These four types of reactions are classified by examining the numbers and types of

reactants and products.

1. Synthesis Reaction: A + B C

2Mg + O2 2MgO

2. Decomposition Reaction: AB CD

NH4NO

3 N

2O + 2H

2O

3. Single Displacement Reaction: A + BC B + AC

Cu + 2AgNO3 Cu(NO3) + 2Ag

4. Double Displacement Reaction: Ax + By Ay + Bx

Pb(NO3) + 2KI PBI2 + 2KNO

3

5. Combustion Reaction: C3H

8 + 5O

2 3CO

2 + 4H

2O

A combustion reaction is a compound that reacts with oxygen to form oxides and energy. These

are mostly carbon-containing compounds (hydro-carbons).


Studying Matter and Its Changes

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