Key to the review
for the semester
exam
Define the following terms
Chemical change- transformation of one
or more substance into a different
substance with different properties
Density- Mass of object divided by its
volume
Extensive property- depend upon the
amount of matter present
Ex: mass, volume
heat energy, length
Intensive Property- doesn’t depend on
amount of matter present and remain
constant
Ex: density,
conductivity, solubility
Physical Change- change in substance that
does not change identity
Covalent Bond- bond between 2 nonmetals
Ion- atoms and molecules with a net
electric charge due to the loss and gain of
1 or more molecules
Ionic Bond- metals and non-metals bond
Isotope- atoms with same amount of
numbers of protons but different numbers
of neutrons
Oxidation Number- total numbers of
electrons that an atom either gains or
losses in order to bond
Average atomic mass- average mass of all
isotopes which are recovered from Earth’s
crust
Electronegativity- ability of an atom to
attract electrons toward itself, fluorine is
special because it has the most
electromagnetic
1. Explain how you can tell that a chemical change has occurred.
Color, odor, light, heat, gas, ppt.
2. Explain how to calculate average atomic mass.
(atomic massx relative abundance/100) + ( atomic mass x RA/100) + ……… = Avg. Atomic
mass
Isotope
Mass Number (grams)
Percent Abundance (%)
A
12.2
15
B
13.1
50
C
14.9
35
3. What is the average atomic mass of the element above?
(12.2 x 15/100) + (13.1 x 50/100) + (14.9 x 35/100) + 13.595 amu.
4. What type of bond is formed between elements with a large difference in
electronegativity?
Ionic if the difference is 2 and polar covalent if the difference is 0.3-1.9.
5. Draw lewis structures for NH3 and BH3. What is the VSEPR shape of each molecule?
Draw the VSEPR shape and explain why these 2 molecules have a different shape.
6. Compare and contrast fission and fusion. Where do these reactions occur? We use
fission for power but not fusion, even though fusion produces more power. Why don’t
we use fusion?
Fission – Splitting of a large atom into 2 or more smaller atoms.
Fusion – Fusing of 2 or more lighter atoms into larger ones.
7. What is the identifying characteristic of noble gases?
Unreactive, stable, conduct electricity, fluorescence, odorless, colorless.
8. How does surface area affect the rate of dissolving?
More particles are in that area where solute
9. Explain how the properties of metals change as they are heated.
Midterm Practice Questions
Multiple Choice
Identify the choice that best completes the statement or answers the question.
_A___ 1. What is the formula for the compound formed by lead(II) ions and chromate ions?
a. PbCrO4
c. Pb2(CrO4)3
b. Pb2CrO4
d. Pb(CrO4)2
_C___ 2. What is the formula for aluminum sulfate?
a. AlSO4
b. Al2SO4
c. Al2(SO4)3
d. Al(SO4)3
__A__ 3. Name the compound Ni(ClO3)2.
a. nickel(II) chlorate
b. nickel(II) chloride
c. nickel(II) chlorite
d. nickel(II) peroxide
__A__ 4. The average atomic mass of an element is the average of the atomic masses of its
a. naturally occurring isotopes.
c. radioactive isotopes.
b. two most abundant isotopes.
d. artificial isotopes.
__A__ 5. A prospector finds 39.39 g of pure gold (atomic mass 196.9665 amu). She has
a. 1.204  1023 atoms of Au.
c. 4.306  1023 atoms of Au.
23
b. 2.308  10 atoms of Au.
d. 6.022  1023 atoms of Au.
_B___ 6. A sample of tin (atomic mass 118.71 amu) contains 3.01  1023 atoms. The mass of the sample is
a. 3.01 g.
c. 72.6 g.
b. 59.3 g.
d. 11 g.
__C__ 7. Which of the following is an extensive property of matter?
a. melting point
c. volume
b. boiling point
d. Density
__B__ 8. Which of the following is an intensive property of matter?
a. amount of energy
c. volume
b. density
d. mass
_C___ 9. The relationship between the mass m of a material, its volume V, and its density D is
a. D = mV.
c. D = m/V.
b. D = V/m.
__B__ 10. 0.25 g is equivalent to
a. 250 kg.
b. 250 mg.
d. D = m + v.
c. 0.025 mg.
d. 0.025 kg.
__C__ 11. The number of significant figures in the measurement 2010 cm is
a. 1.
c. 3.
b. 2.
d. 4.
__C__ 12. Which of the following does not increase the rate of dissolving a solid in water?
a. raising the temperature of the water
b. stirring the solution
c. using larger pieces of solid
d. crushing the solid
_A___ 13. Increasing the surface area of the solute
a. increases the rate of dissolution.
b. decreases the rate of dissolution.
c. has no effect on the rate of dissolution.
d. can increase, decrease, or have no effect on the rate of dissolution.
_B___ 14. Which of the following lists atomic orbitals in the correct order they are filled according to the Aufbau
principle?
a. 1s 2s 2p 3s 4s 3p 3d 4p 5s
b. 1s 2s 2p 3s 3p 4s 3d 4p 5s
c. 1s 2s 2p 3s 3p 4s 4p 3d 4d
d. 1s 2s 2p 3s 3p 3d 4s 4p 5s
_D___ 15. The element with electron configuration 1s2 2s2 2p6 3s2 3p2 is
a. Mg (Z = 12).
c. S (Z = 16).
b. C (Z = 6).
d. Si (Z = 14).
_C___ 16. The electron notation for aluminum (atomic number 13) is
a. 1s2 2s2 2p3 3s2 3p3 3d1.
b. 1s2 2s2 2p6 3s2 2d1.
c. 1s2 2s2 2p6 3s2 3p1.
d. 1s2 2s2 2p9.
__B__ 17. What is the formula for zinc fluoride?
a. ZnF
b. ZnF2
c. Zn2F
d. Zn2F3
_A___ 18. Name the compound Fe(NO3)2.
a. iron(II) nitrate
b. iron(II) nitrite
c. iron(III) nitrate
d. iron(III) nitride
Chemistry Midterm Review Part 2
Define the following Terms
Nuclear reaction
1. Explain alpha decay and give 1 example of a nuclear equation that shows alpha decay.
2. Elements can be solids, liquids, or gases at room temperature. Explain how melting points and
boiling points determine what state matter an element will be at room temperature.
Solids high MP
Liquids High BP
3. Are the melting points and boiling points of solids high or low?
4. Are the melting points and boiling points of gases high or low?
High
Low
5. What property of water gives it unique qualities?
H bonding
6. Describe the differences in charge between alpha, beta, and gamma radiation.
7. Draw a picture of an alpha and a beta particle moving between 2 electrodes. One electrode is
positively charged and the other is negatively charged.
8. Draw the lewis dot structures for Cl2 Br2 N2 and O2
9. You start with 24g of a radioactive isotope. How many grams will be left after 2, 3 , 4, and 5 half
lives?
10. List 3 changes that are physical changes
11. Draw the electron dot structures for N, P, C, S, and Se
12. The atoms in which period on the periodic table have the largest radii? Which period has the
smallest radii?
13. A beaker containing 2.20 L of 1.50 M LiCl is allowed to sit undisturbed in a warm
room. After three hours, 275.0 mL of water has evaporated. What is the new
concentration to the nearest hundredth of the lithium chloride solution?
14. If you have a sample of an unknown substance what types of experiments could you conduct to
see if it is a pure substance?
15. What were the conclusions that resulted from Rutherford’s gold foil experiment?
16. What is the percent by mass of sulfur in sulfuric acid?
S= 32/98x100 =
Midterm Review Part 2
__A__ 1. Balance the following equation:
____
a.
c.
b.
d.
__B__ 2. Which of the following processes always decreases the number of protons by an even number?
a. fusion
c. alpha decay
b. beta decay
d. fission
_B___ 3. Alpha particles are
a. electrons.
b. helium nuclei.
c. electromagnetic waves.
d. neutrons.
___A_ 4. Beta particles are
a. electrons.
b. helium nuclei.
c. electromagnetic waves.
d. neutrons.
__D__ 5. Which of the following is the symbol for an alpha particle?
a.
c.
b.
d.
__C__ 6. Which of the following is the nuclear symbol for a beta particle?
a.
c.
b.
d.
__C__ 7. A solution containing 35 g of Li2SO4 dissolved in 100 g of water is heated from 10°C to 90°C. According
to information in the figure, this temperature change would result in
a. an additional 5 g of Li2SO4 in solution.
b. an additional 30 g of Li2SO4 in solution.
c. 5 g of Li2SO4 precipitate.
d. no change in Li2SO4 concentration.
__C__ 8. According to saturation curves shown in the figure, which of the following solutions is supersaturated?
a. 40 g of NaCH3COO in 100 g of water at 40°C
b. 140 g of NaCH3COO in 100 g of water at 80°C
c. 80 g of NaCH3COO in 100 g of water at 40°C
d. 80 g of NaCH3COO in 200 g of water at 40°C
___A_ 9. Which is the correct Lewis structure for SiF4?
a.
b.
c.
d.
__D__ 10. According to VSEPR theory, what is the shape of a molecule of NBr3?
a. bent
b. trigonal-planar
c. tetrahedral
d. trigonal-pyramidal
__A__ 11. The half-life of an isotope is the time required for half the nuclei in a sample to
a. undergo radioactive decay.
c. undergo nuclear fusion.
b. undergo nuclear fission.
d. react chemically.
__C__ 12. How many half-lives are required for three-fourths of the nuclei of one isotope in a sample to decay?
a.
c. 2
b.
d. 3
__b__ 13. Carbon-14 has a half-life of 5715 years. If a sample of carbon-14 has an original mass of 10 g, the amount
remaining at the end of 11 430 years will be
a. 2.5 g.
b. 5 g.
c. 10 g.
d. 50 g.
__C__ 14. A sample of tin (atomic mass 118.71 amu) contains 3.01  1023 atoms. The mass of the sample is
a. 3.01 g.
c. 72.6 g.
b. 59.3 g.
d. 11 g.
__D__ 15. Using the Stock system of nomenclature, Cr2(SO4)3 is named
a. chromium(II) sulfate.
b. chromic sulfate.
c. dichromium trisulfate.
d. chromium(III) sulfate.
__B__ 16. What is the formula for copper(I) oxide?
a. CuO
b. Cu2O
c. CuO2
d. Cu2O2
__A__ 17. A solubility table shows that almost all compounds of Group 1 metals are soluble in water. This general
rule tells you that
a. KI is soluble.
b. RbNO3 is insoluble.
c. CaCl2 is soluble.
d. CO2 is soluble.
__D__ 18. Which of the following compounds is soluble in water?
a. PbBr2
b. MgCl2
c. BaSO4
d. CaCO3
__C__ 19. Which of the following compounds is insoluble in water?
a.
b.
c.
d.
(NH4)2S
Na2O
LiOH
Al2O3
_C___ 20. If the amount of dissolved solute in a solution at a given temperature is greater than the amount that can
permanently remain in solution at that temperature, the solution is said to be
a. saturated.
b. unsaturated.
c. supersaturated.
d. diluted.
__A__ 21. All of the KBr that will dissolve in a solution has dissolved, and several undissolved crystals remain on
the bottom of the beaker. The solution is
a. saturated.
b. supersaturated.
c. unsaturated.
d. at the incorrect pressure to dissolve the solid.
__A__ 22. How many molecules are there in 5.0 g of methyl alcohol, CH3OH?
a. 9.4 1022
c. 3.6 1024
24
b. 3.0 10
d. 3.8 1024
__B__ 23. What is the percentage composition of CF4?
a. 20% C, 80% F
b. 13.6% C, 86.4% F
c. 16.8% C, 83.2% F
d. 81% C, 19% F
__C__ 24. What is the mass percentage of chlorine in NaCl?
a. 35.45%
c. 60.7%
b. 50%
d. 64.5%
Problem
1. Draw a ball-and-stick model of a water molecule. Label that atoms, include the polarities of the bonds
using arrows, and indicate net molecular dipole.
2. A solution contains 85.0 g of NaNO3, and has a volume of 750. mL. Find the molarity of the solution.
(molar mass of NaCl = 58.44 g/mol) Round to the nearest hundredth
Molority = MASS/MM/ LITERS OF SOLUTION
M = 85G/85G/MOLE / 0.750 L = 1.33 moles/Liter
3. What is the molarity of a solution of sucrose, C12H22O11, that contains 125 g of sucrose in 3.50 L of
solution? (molar mass of C12H22O11 = 342.34 g/mol) round to the nearest hundredth
M = 125/342/3.5 L = 0.10 M