Review guide for Chemistry’s First Semester Exam

Here are the learning goals with some sample questions that will help you prepare for the semester exam. The learning goals appear in bold font and the problems are in regular. Pages of your text book are sometimes given, in case you need more support. All of the materials handed out in class are available to be downloaded from Mr. Botella’s website. Go to Chemistry and look under handouts. You might need more paper for answering the questions.

Unit 1 Thinking like a Chemist I will be able to… Identify common lab equipment (graduated cylinder, beaker, test tube)

1. Sketch each of the following glassware:

a. Beaker

b. Flask

c. Graduated cylinder

d. Test tube

Properly measure objects using lab equipment (eg. volume, length, mass). 2. What is the length of the following object (Remember to guess up to one more digit from instrument’s precision

and do not forget the units!)

The length of the object is 7.45 cm approximately

Convert numbers that are in scientific notation into numbers written in ordinary notation and vice versa.(P.48 TXT)

3. Write the following numbers into correct scientific notation: a. 1023 = 1.02x103 d. -56894 = -5.69x104

b. 0.000054 = 5.4x10-5 e. -0.000593 = -5.93x10-4

c. 125.89 = 1.26x102 f. 4897x104 = 4.90x107

4. Write the following numbers into regular notation

a. 1.25x103 = 1250 d. 165.89x102 = 16589

b. 0.00034x10-2 = 0.0000034 e. 9.573x10-4 = 0.0009573

c. 4.45x10-6 = 0.00000445 f. -2.36x104 = -23600

Do addition, subtraction, multiplication, and division of numbers written in scientific notation (P. 48 and 56 TXT) 5. Find the correct value for the following operations without a calculator

a. 2.00x10-2 + 4.00x10-1 = 4.2x10-1

b. 9.00x109 – 3.00x108 = 8.7x109

c. 4.00x104 * 2.00x102 = 8x106

d. 5.00x10-4 * 5.00x104 = 25x100 = 2.5x101

e. 1.50x106 / 3.00x103 = 5x102

6. Find the correct value for the following operations. You can use your calculator this time.

f. 3.65x10-5 + 6.19x10-6 = 4.27x10-5

g. 1.87x109 – 8.7x108 = 1x109

h. 4.67x106 * 6.95x103 = 3.25x1010

i. 9.56x106 / 3.20x10-2 = 2.9x108

Define and write the equation for density 7. Define density and write its equation

Density is defined as the ratio between mass and volume (D=m/v). Density measure how compact matter is. A denser object will have the same amount of matter in a smaller volume

Know the value for the density of water 8. Write the value of density for pure water: 1 g/cm3

Know what makes one substance more dense than a different substance

9. If you have 1 kg of lead and 1 kg of cotton, which takes up more space? Since lead is denser than cotton, 1 kig of lead takes less space than 1 kg of cotton

10. If you have a volume of 10 cm3 of lead and another volume of 10 cm3 of cotton, which one is heavier? Since lead is denser than cotton, 10 cm3 of lead has a lot more matter than 10 cm3 of cotton

Know that the density of a substance does not depend on the size of the object. 11. Explain what happens to the density of a homogenous object (say a piece of paper) when we cut it in half

The density does not change when we cut a homogenous object in half. The new pieces will have half the mass and will take half the volume.

Calculate the density of an object, given its mass and volume. 12. Find the density of a plastic cube that has a volume of 3cm3 and a mass of 6.2 g

v=3 cm3 = 3 ml D=m/v = 6.2 g / 3 cm =2.07 g/ml m=6.2 g D=?

Calculate the density of an object, given its mass and volume. 13. Find the volume of the ball that has a mass of 500 g and a density of 1.68 g/ml

m= 500 g D=m/v therefore v = m/D = 500 g / 1.68 g/ml = 297.6 ml D= 1.68 g/ml V=?

Calculate the mass of an object, given its density and volume. 14. Calculate the mass of a portfolio if you know its density is 2.3 g/ml and its volume is130 cm3

m= ? D=m/v therefore m = v*D = 130 ml * 2.3 g/ml = 299 g D= 2.3 g/ml V= 130 cm3 = 130 ml

Predict an objects relative density based on whether it floats or sinks in a liquid of known density (such as water).

15. You place three liquids that cannot mix in a beaker. You know the one labeled A is water (density of 1 g/ml), B is an oil (density .7 g/ml), and C is a mysterious liquid whose density is 0.89 g/ml. Which of the liquids would be on top, and which in the bottom. Denser liquids go below less dense liquids. Water (A) will be on the bottom, mysterious liquid C will be in the middle and the oil (B) will be on top.

Know the metric prefixes: kilo, centi, milli, micro 16. Define what each prefix means in terms of the unit value. For example, Kilo means 1000 times de unit value

a) Centi is a hundredth of the unit

b) Mili is a thousandth of the unit

c) Micro is a millionth of the unit

Define metric system, unit conversion and conversion factors 17. Define the metric system and indicate in what number is the metric system based

Metric system is a system of measurements based on the number 10

18. Define metric conversion by indicating what do we use this for Metric conversion is used for transforming one unit in the metric system to another one. For example, to convert a number of kilometers to centimeters

19. Define a conversion factor (what is a conversion factor?) Conversion factors tell the equivalence between different units. For example 1 km = 100000 cm (1x105)

Convert from one metric prefix to another using the table of metric prefixes. 20. Do the following metric conversions:

a. 53 m = 5300 cm c. 0.9 mg = 0.0009 g = 9x10-4 g

b. 145 kl 14500000 cl d. 67 mm = 0.000067 km = 6.7x105 km

Solve unit conversion problems involving more than one conversion factor.

a. You heard a loud thump! while walking the dog one evening. You turned around the broken tree to find a meteorite! You called your meteorite hunter friend in Paris and she asks about the weight of the meteorite in kilograms. You only have a balance that reads in ounces and find the meteorite’s mass to be 53 ounces. How many kilograms is this equal to (2.2 pounds = 1 kilograms; 16 ounces = 1 pound)? Use conversion factors to solve this problem in the space below. Weight in ounces = 53 oz convert to kilograms

53��

1∗ 1�

16��∗1��

2.2�= 1.51��

b. A friend tells you he measured an oceanic current’s speed to be 5 m/s. How fast is that in miles per hour? Use

the following conversion factors to solve the problem :1 mile = 1508 m, 1 km = 1000 m; 1 h = 60 min; 1 min = 60 sec Speed of current: 5m/s convert to miles per hour.

5�

�∗1����

1508�∗60�

1���∗60���

1ℎ�= 11.9

�����

ℎ�

Unit 2 Classification of Matter Know these terms:

Use these terms to complete the web:

matter pure substance

atom homogenous mixture

element solution

mixture heterogenous mixture

molecule compound

Can be either

Review the symbols and names of commonly used elements (p.22)

Identify the symbols and names of the 7 diatomic elements:

Hydrogen, H Oxygen, O Nitrogen, N Chlorine, Cl, Bromine, Br

Iodine, I Fluorine, F (remember HONClBrIF)

Distinguish between an element and a compound symbolically

Identify each as an Element (E) or a Compound (C )

E Au E Br2 C H2O C CO2 E He C NaCl

Describe the difference between an element and a compound

Element: An element is made out of the same type of atoms

Compound: Compouinds are made out of at least two different types of atoms that are combined chemically

Distinguish between an atom and a molecule symbolically

Identify the following as an atom (A) or a molecule (M)

MATTER Anything that has weight and takes up space

Homogeneous

Matter which looks the same throughout

Heterogeneous Matter which looks different throughout

Pure substance A kind of material with the same

composition throughout

Mixture Made up of 2 or more substances; are

physically combined; composition varies

throughout

Element A substance which cannot be

broken down further

Solution Special Case: A homogenous mixture that is

physically combined

Compound Made up of more than one type of

atom; substance can be broken

down by simple chemical means

Atom Smallest unit of an

element

Molecule Smallest unit of a

compound

A He M NaCl M CuBr A P M SO4 A Mg

Describe the difference between an atom and a molecule

Atom: An atom is the smallest unit of an element

Molecule: Molecules are made of more than one atom chemically combined. The atoms can be of the same or

different type (which means that diatomic elements make molecules by having two of their atoms chemically

combined, for exampleH2)

Identify examples of a homogenous mixture and a heterogenous mixture

Identify each of the following mixtures as homogeneous (HO) or heterogenous (HE)

HO Table Salt (NaCl) HO Gold (Au) HEChocolate Chip Cookie Dough

HO Lemonade HO Shampoo HO Well-Mixed Salt Water

Describe the difference between physical and chemical changes

Change in Matter

Identify examples of chemical and physical changes

Label the following as a chemical change (C) or a physical change (P)

P glass breaking C burning toast C frying an egg C spoiling (rotting) food

C a rusting nail P making salt water P melting ice cream P mowing the lawn

Identify examples of chemical properties and physical properties

Identify the following as a chemical property (C) or a physical property (P)

P Color P Taste C Ability to rust P Boiling point P Ability to dissolve

P Density P Odor P Melting point C Flammability P Freezing point

Physical Change

Definition: Physical change is a change

in matter that does not change the

composition of matter (all molecules

remain as the same molecule).

Signs of physical changes:

Change in shape (broken glass)

Change in state of matter (evaporation,

melting)

Chemical Change

Definition: Chemical change is a change in matter in

which the composition of molecules changes.

Signs of chemical changes:

Change in color

Change in odor

Change in temperature

Formation of a precipitate

Release of (light (flames, sparkles,light)

Formation of bubbles (except outgassing by pressure

differences)

Unit 3: Atomic structure, Periodic Table, and Sublevel Notation Explain the difference between science and pseudoscience Define: atom, neutron, proton, electron, atomic mass, atomic number

An _________ is the smallest unit of matter. An electron is a negatively charged particle, with essentially no mass. Now draw a sketch of a K atom, showing the correct location and number of neutrons, protons, and electrons: Define: ion, cation, anion, oxidation number Ion is any charged particle. Ions have a charge because they have different amount of protons and electrons. Cation is a positive ion Anion is a negative ion Oxidation number is the charge of an ion Match the items to the statement. Some items can be used more than once, and some statements have two

correct answers. Fill in all answers that apply!

8. Has/have more electrons than protons. A

9. Not an ion. C

10. Cation(s) D and B

Characteristics of Pseudoscience

Based in believes, not evidence

Untestable claims

Secretive (Not tested by others)

Relies in confirmation, not

contradiction

Criteria for Scientific Models

Based on evidence (data and facts)

Testable claims

Continuously tested by others

Relies on contradictions (valid if no

contradictions are found)

19

K

39.098

This is the number of protons positively charged particles. This

is also referred to as the atomic number

This is the average atomic mass which you can calculate by adding the

number of protons and neutrons

A. Cl-2

B. K+1

C. F

D. Al+3

2 8 8 +p = 19

N = 20 1

11. Anion(s) A

12. Has/have gained electrons. A

13. Has/have lost electrons. D and B

Looking at the ions in the box above, circle the oxidation numbers. Define oxidation number in your own

words:

Oxidation number is the charge of an ion. Oxidation numbers above are the -2 above Cl, +1 above K and +3 above Al

Understand how the periodic table is organized. Know where important families are located. For more

help, read chapter 5, sections 1 & 2 (p. 124-140) in your textbook.

Using the periodic table above, color the Noble Gases red. Give the number of valence electrons of this family: 8 Color the Halogens green. Give the number of valence electrons of this family: 7 Circle the Diatomic Elements. Shade in the Metalloids. On what side of the Metalloids are Metals located? Left Non-metals? Right

The direction of a Period: ↔ and a Family: ↕ Describe what elements in the same period have in common: Elements in the same period have the same number of energy levels Describe what elements in the same family have in common: Elements in the same family have the same valence electrons, and same type of last sublevel Describe how properties (atomic radius, ionization energy, valence electrons) change going across a period

or down a column (family). Read p. 142-148 in your textbook.

Define Periodic and make a drawing to show what a periodic trend looks like: Periodic means: a property is said to be periodic if it repeats over and over Periodic looks like:

Describe the main characteristics of different types of elements (metals, metalloids, non-metals). See p. 17-19 in your book. Fill in the Venn diagram below to show which properties are unique to metals, metalloids, and non-metals, and which properties two groups may share:

Write the electron configuration for any element (sublevel notation) by reading the periodic table Give the sublevel notation for the following elements: Carbon 1s22s22p2

Define: Atomic Radius

The distance between the edge of an atom and its

center since it is hard to define the edge of an

atom, it is defined as half the distance between the

centers of two identical adyacent atoms

How does this property change going across a

period? decreases

…down a family? Increases

Define: Ionization Energy

The energy required to remove an electron from

the atom

How does this property change going across a

period? Increases

…down a family? decreases

Metals Non-Metals Metalloids

Shinny

Silver grey (save Cu

and Au)

Good conductors of

energy and electricity

Maleable (make sheets)

and ductile (cables)

Solid (save Hg)

opaque

multicolor

Poor conductors of

energy and electricity

Britle

Solid (s), liquid (Br),

and gases (N, O, H,

etc.)

Conduct

like metals

when

impure

Poor

conductors

when pure

Lead 1s22s22p63s23p64s23d104p65s24d105p66s24f145d106p2

Copper 1s22s22p63s23p64s23d9 Identify the following elements according to their sublevel notations: 1s22s22p63s23p5 Chlorine (Cl) 1s22s22p63s23p64s23d104p65s24d9 Silver (Ag) 1s22s22p63s23p64s23d104p65s24d105p66s24f145d5 Rhenium (Re) Write the electron configuration using the noble gas short hand Give the sublevel notation for the following elements, using the noble gas short hand Cl [Ne]: 3s23p5

Pr [Xe]: 6s24f3

Sb [kr]: 5s24d105p3

Find the oxidation number of elements by: a) drawing the atomic sketch of the element or b) looking at the periodic table Draw the atomic sketch for As AND show its number of valence electrons using an electron dot symbol, for example, As Draw the atomic sketch for Ba AND show its number of valence electrons using an electron dot symbol Ba Describe how you can tell the number of valence electrons from looking at the atomic sketch: The valence electrons are the

electrons in the last sublevel (actually, thee electrons in the S and P sublevels only)

What is another way you can tell the number of valence electrons, by looking at the periodic table? For the elements in the S and P blocks, the number of their column is equal to the number of valence electrons. This is not true for elenments in d and f blocks, since all of them have 2 valence electrons.

X

2 8 18 +p = 33

N = 42 5

2 8 18 18 8 2 +p = 56

N = 81

Unit 4: Copper lab, Writing formulas, Naming compounds Define Reactant and products, precipitate, exothermic and endothermic reactions and signs of each Write the definition of the following terms:

1. Reactants and products: Reactants are thesubstances that participate in a chemical reaction as the starting points. Products are the substances that form in a chemical reaction

2. Precipitate: Precipitate is a solid that forms within a liquid as a product of a chemical reaction 3. Exothermic reaction and endothermic reaction An exothermic reaction releases energy to its

environment (feels hot), and an endothermic reaction absorbs energy from its environment (feels cold) Define the symbols (aq), (s), (l), (g), and explain when to use these symbols In the reaction below, explain what do the symbols (aq), (l), (g) mean. Cl2(g) + KBr(aq) → KCl(aq) + Br2(l)

(aq) states that the substance is dissolved in water (l) states that the substance is a liquid with no water (g) states the substance is a gas (s), not present in this reaction, states the substance is a solid

What is the difference between the following sy,mbols for hydrochloric acid HCl(aq) and HCl(l)

HCl(l) is pure hydrochloric acid with no water, but still a liquid, while HCl(aq) is hydrochloric acid that has been dilited in water.

Describe five signs that a chemical change has occurred List five evidences that a chemical change has occurred, and provide examples for each from the copper lab

Change in color: When the solod cipper was mixed with the colorless nitric acid and formed a deep blue copper II nitrate Change in odor: In the same reaction nitrogenmonoxide wsa fromed and smelled bad Change in temperature: Whan aluminium wire was added to the copper II chloride and the beaker got very hot Formationo of a precipitate: The warming up of copper hydroxide produced the precipitate of copper II oxide Bubbling gas: the reaction of aluminium and copper II nitrate released a lot of gas

Describe the following laboratory techniques: decanting, water bath and gravity filtration Describe each of the following lab procedures by indicating what is the main goal for using the procedure, and indicate when you would use them.

1. Decanting Decanting is a technique used for removing excess water from a mixture of solid and liquid or two liquids that do not mix (immiscible). The beaker is tilted until to pour the upper liquid, and a stirring rod is placed at the edge of the mouth of the beaker to allow the liquid to flow down around it.

2. Water bath A water bath is used when we want to keep the temperature at a certain value. A cold water bath is used to cool down the reaction while a hot water bath is used to warm it up

3. Gravity filtration Gravity filtration is used for separating liquids from solids. A filter is folded in fourths and placed on a funnel. The liquid is poured into the filter and another beaker isplaced below the funnel to recover the filtered liquid. The solid is removed from the filter at the end.

Describe the criss-cross method for writing chemical formulas based on the fact that compounds have no overall charge. Write down the steps you would take for writing the chemical formula of a given compound

1. Find the oxidation number ofr the ions involved in the compound 2. Write the cation to the left (+), and the anion (-) to the right

3. If the sum of the oxidation numbers is different from zero, then write as the subscript of the cation the oxidation number of the anion, without the sign, and the oxidation number of the anion, without the sign, as the subscript of the cation.

Write the correct chemical formula for the following compounds:

1. potassium chromate K2(CrO4)

2. magnesium nitrate Mg(NO3)2

3. copper I phosphate Cu3(PO4)

4. copper II phosphate Cu3(PO4)2

5. ammonium sulfate (NH4)2(SO4)

6. iron II dichromate Fe(Cr2O7)

7. iron III dichromate Fe2(Cr2O7)3

8. copper I bromide CuBr

9. copper II bromide CuBr2

10. magnesium oxide MgO

Write the correct name for a compound when you are given its chemical formula (in symbols) Write down the steps you would take for naming compounds given its formula Write the correct name for the following compounds:

1. K3N potassium nitride 2. Fe2(CO3)3 Iron III carbonate 3. Sn(Cr2O7) Strontium II dichromate 4. (NH4)2(SO4) ammonium sulfate 5. Ag2(SO3) Silver sulfate 6. NO3 Nitrogen trioxide 7. Li(OH) Lithium hydroxide 8. SF6 Sulfur hexaflouride 9. C I4 Carbon tetraiodide 10. Pb(C2H3O2)2 Lead acetate 11. BaCl2 Barium II Chloride 12. Cs3P2 Caesium II phosphide 13. Sr(NO2)2 Strontium II nitrate 14. Cr(SO4) Chromium II sulfate 15. Zn3(PO4)2 Zinc II phosphate

Write a correct chemical reaction, including the reactants and products

Write the symbols for the following equation, including the symbols (aq), (l), (g) ot (s) for each compound. Circle the reactants and square the products

1. Silver sulfate dissolved in water and pieces of sodium yield a precipitate of silver and a solution of sodium sulfate dissolved in water

Ag2(SO4)(aq) + Na Ag(s) + Na2(SO4)(aq)

2. The solutions of Lead II nitrate and potassium iodide, both dissolved in water, produce a precipitate of lead iodide and the diluted solution of potassium nitrate

Pb(NO3)2(aq) + KI(aq) PbI2(s) + K (NO3)(aq)

Unit 5 Reaction Types and predicting products Define: The five major types of reactions: combination, decomposition, single replacement, double replacement, and combustion of a hydrocarbon. Identify the following reaction types: A + B → AB Combination (synthesis in your textbook) A + BC → B + AC Single replacement by a metal (if it where a single replacement by a halogen it would be A + BC C + BA CxHy + O2 → CO2 + H2O Combustion of a hydrocarbon AB → A + B Decomposition AB + CD → AC + BD Doubl;e replacement Which reaction types have “subtypes” that require you to use the chart for predicting products? Decomposition and Single replacement Describe the characteristics for the five types of reaction that can be used for identifying them. A reaction with one reactant must be decomposition A reaction with one product must be Combination A reaction with a compound whose formula is CxHy and whose products are CO2 and H2O must be: Combustion of a hydrocarbon A reaction with two compounds as reactants and products is: Double replacement A reaction with one element and one compound as reactants is: Single replacement (when the element is not oxygen and the compound a hydrocarbon) Identify the five types of reactions Write the type of reaction for the following chemical reactions

Combination 1.Al + S Al2S3

Decomposition (binary) 2. Au2O3 Au + O2

Combination 3. H2 + N2 NH3

Decomposition (binary) 4. NaF Na+ F2

Single replacement by a metal 5. Zn + HNO3 H2 + Zn(NO3)2

Double replacement 6. LiOH + H2SO4 Li2SO4 + H2O

Single replacement by halogen 7. Cl2 + NaI NaCl + I2

Single replacement by metal 8. K + H2O KOH + H2

Double replacement 9. AgNO3 + AlCl3 AgCl + Al(NO3)3

Combustion of a hydroicarbon 10. CH4 + O2 CO2 + H2O

Identify the subtypes of reaction for decomposition and single replacement Write the subtype of each reaction below. Use your chart of subtypes to help you. Decomposition of a metal chlorate 1. KClO3 → KCl + O2 Decomposition of a metal hydroxide 2. NaOH → Na2O + H2O Single replacement by a halogen 3. Cl2 + CaI2 → CaCl2 + I2 Decomposition of a binary compound 4. CaCl2 → Ca + Cl2 Decomposition of a metal carbonate 5. CaCO3 → CaO + CO2 Single replacement by a metal 6. Zn + AlCl3 → ZnCl2 + Al Predict the products of a reaction (remembering to use criss-cross and HONClBrIF

Write the products of the following reactions. Indicate the type of reaction as well 1. Decomposition of a binary compound Au2O3 Au + O2

2. Combination H2 + N2 H3N more commonly written as NH3

3. Single replacement by metal Zn + HNO3 Zn(NO3)2 + H2

4. Double replacement LiOH + H2SO4 Li2(SO4) + H2O

5. Single replacement by halogen Cl2 + NaI NaCl + I2

6. Combination Al + N2 AlN3

7. Single replacement K + H2O K(OH) + H2

8. Double replacement AgNO3 + AlCl3 Al(NO3)3 Cl3 + AgCl

9. Combustion of a hydrocarbon CH4 + O2 CO2 + H2O

10. Decomposition of metal carbonate Fe2(CO3)3 Fe2O3 + CO2

11. Single replacement by metal Cr + H2SO4 Cr(SO4)2 + H2

Unit 6 Balancing Reactions

Relate the conservation of matter to the rearrangement of atyoms in a chemical formula

Explain what is the purpose of balancing equations

Write and interpret a balanced chemical equation for a reaction, and relate conservation of matter to the

balanced equation

Determine if the following equations are balanced or not

1. CaCO3 → CaO + CO2 It is balanced

2. Al + 3 N2 AlN3 It is not balanced

3. K + H2O K(OH) + H2 It is not balanced

Balnce the following reactions

1. 2 KClO3 → 2 KCl + 3 O2

2. 2 NaOH → Na2O + H2O

3. Cl2 + CaI2 → CaCl2 + I2

4. 2 NaCl → 2 Na + Cl2

5. 3 Zn + 2 AlCl3 → 3 ZnCl2 + 2 Al

6. 2 Au2O3 4 Au + 3 O2

7. 3 H2 + N2 2 H3N

8. Zn + 2 HNO3 Zn(NO3)2 + H2

9. 2 LiOH + H2SO4 Li2(SO4) + 2 H2O