Unit 3 Review Questions with answers
Molecular Geometry
1.
2.
3.
4.
5.
6.
Atoms that share electrons form a _______ bond?
Covalent
Atoms that accept and donate electrons form a _____ bond? Ionic
What does VSEPR stand for? Valance Shell Electron Pair Repulsion Theory
T or F: Electron pairs orient themselves in order to minimize repulsive forces. T
Non-bonding electron pairs are called? Lone-pairs
Fill-in the following chart
Name
# of Lone Pairs
# of Bonding Pairs
Bond Angle
Linear
0
2
180
Bent
2
2
104.5
Trigonal Planar
0
3
120
Trigonal Pyrimidal
1
3
107
Tetrahedral
0
4
109.5
7. Draw the Lewis Dot Structure for PBr3.
8. Name and draw the shape for PBr3.
Trigonal Pyrimidal
Polymer
9. What is a polymer? A very large molecule formed by the covalent bonding of repeating
small molecules, known as monomers or mers.
10. What is a very large molecule commonly created by polymerization of smaller subunits called?
Macromolecule
11. Polymers are made of up __________ called _________. Many units, Mers
12. How can you make polymers stronger? Increasing bond strength (single to double ot triple)
Radiation & Decay
13. The process by which nuclei emit particles and rays is called? Radioactivity
14. The penetrating rays and particles emitted by a radioactive source is called? Radiation
15. Name the 3 types of radiation. Alpha, Beta and Gamma
16. Which type of radiation gives off a particle containing two protons and two neutrons? Alpha
17. Which type of radiation gives off a high speed electrons from a neutron breaking apart? Beta
18. Which type of radiation has the highest energy radiation and occurs in an excited nucleus?
Gamma
19. Rank Alpha, Beta and gamma radiation based on highest matter penetrating to lowest matter
penetrating.
Gamma, Beta, Alpha
20. The time required for one-half of the nuclei of a radioisotope sample to decay is called? Halflife :
21. What is the difference between fission and fusion?
Fission: The splitting of a nucleus into smaller fragments. Fusion: The process of combining
nuclei to produce a nucleus of greater mass.
Potential Energy Diagrams
22. What is Av (Activation energy)? Minimum energy required by colliding particles in order to
react or get over the hump.
23. Which letters are the reactants and which are the products? A+B, C+D
24. Does the graph represent an endothermic or exothermic reaction? Exo
25. How much energy is required to turn reactants into products?100-40 = 60
26. What are the four factors that affect reaction rates?
27. What is a catalyst? substance that increases the rate of a chemical reaction without being
changed by the reaction.
28. How does a catalyst affect the magnitude of the activation energy?
Indicators of a chemical RXN
29. Define the following terms: Physical Reaction, Chemical Reaction, Concentration, Surface
Area
Physical Reaction: The matter stays the same, but change in size, shape, or appearance.
Chemical Reaction: The matter changes to a different kind of matter, or change in color.
Concentration: amount of substance dissolved in a certain amount of solvent.
Surface Area: refers to the amount of material that is exposed
30. What are the 4 indicators of a chemical RXN?
1) Precipitate Formation
2) Color Change
3) Formation of bubbles
4) Formation of Heat or Light (Temperature Change)
31. During the experiment, you combined a solution of calcium hydroxide and sodium hydroxide.
The new solution turned white with particles forming and falling to the bottom. There were to
bubbles created and no accurate temperature recording. Which indicators show the presence
of a chemical reaction in the experiment?
1) Color change, 2) Precipitate formation.
Balancing Chemical Equations
32. What is the Law of Conservation of matter state? Law of Conservation of Mater – In a
chemical reaction, no mass is lost or gained.
Balance the following chemical equations
33. __ KOH + __ H3PO4 → __ K3PO4 + __ H2O
3 KOH + 1 H3PO4 → 1 K3PO4 + 3 H2O
34. __ SnO2 + __ H2 → __ Sn + __ H2O
1 SnO2 + 2 H2 → 1 Sn + 2 H2O
Types of Chemical Reactions
35. What are the 6 different types of chemical reactions? Synthesis, Decomposition, Single &
Double Replacement, Acid-Base neutralization & Combustion
36. Which type of chemical reaction always produces CO2, H2O and energy? Combustion
37. If two elements combine to form one product, what type of reaction occurred? Synthesis
38. In a reaction, you have one element reacting with one compound and producing a different
element and a different compound what type of reaction occured? (One element switched with
an element in the compound.) Single Replacement
Determine the type of chemical RXN that occurred
39. C10H8 + 12 O2 ---> 10 CO2 + 4 H2O
Combustion
40. 8 Fe + S8 ---> 8 FeS
Synthesis
41. 2 H2O ---> 2 H2 + O2
Decomposition
42. Mg + 2 H2O ---> Mg(OH)2 + H2
Single Replacement
43. Pb(NO3)2 + 2 KI ---> PbI2 + 2 KNO3
Double Replacement
44. HBr + NaOH ---> NaBr + H2O
Acid-Base Neutralization
Stoichimoetry
45. What is the mole ratio of H2O to Ca(NO3)2 in the following equation? 2H3PO4 + 3Ca(OH)2
6H2O + Ca3PO4
6:3  2:1
46. In the reaction Ca + Cl2 → CaCl2, what is the mole ratio of chlorine to calcium chloride?
a. 2:3 c. 1:2
b. 2:1 d. 1:1
D
47. Calculate the molar mass of CuSO4. 159.5 g/mol
48. Calculate the molar mass of Cr4(P2O7)3. 729.8 g/mol
49. Find the empirical formula from the molecular formula. H8O8 
H2O2
50. How many mole are in 50 grams of water? 2.778 mol
51. How many molecules are in 50 moles of oxygen? 3.01 x10 25 molec
52. How many particles are in 50 g of H2O? 1.67 x 10 23 part.
53. Balance the following equation:___NH3 + ___O2→ ___NO2 + ___H2O
The balanced equation shows that 1.00 mole of NH3requires ___ mole(s) of O2
a. 0.57
b. 1.25
c. 1.33
d. 1.75
e. 3.5
D
54. Find the percent composition of each element in the molecule
ammonium nitrate, NH4NO3
N= 35%
H=5% O=60%
55. A molecule with molecular weight of 180.18 g/mol is analyzed and found to contain 40.00%
carbon, 6.72% hydrogen and 53.28% oxygen.
What are the empirical and molecular formulas of the molecule?
Empirical C5H13
Molecular C10H25
Unit 3 Review Questions
Molecular Geometry
1.
2.
3.
4.
5.
6.
Atoms that share electrons form a _______ bond?
Atoms that accept and donate electrons form a _____ bond?
What does VSEPR stand for?
T or F: Electron pairs orient themselves in order to minimize repulsive forces.
Non-bonding electron pairs are called?
Fill-in the following chart
Name
# of Lone Pairs
# of Bonding Pairs
Bond Angle
Linear
Bent
Trigonal Planar
Trigonal Pyrimidal
Tetrahedral
7. Draw the Lewis Dot Structure for PBr3.
8. Name and draw the shape for PBr3.
Polymer
9. What is a polymer?
10. What is a very large molecule commonly created by polymerization of smaller subunits called?
11. Polymers are made of up __________ called _________.
12. How can you make polymers stronger?
Radiation & Decay
13. The process by which nuclei emit particles and rays is called?
14. The penetrating rays and particles emitted by a radioactive source is called?
15. Name the 3 types of radiation.
16. Which type of radiation gives off a particle containing two protons and two neutrons?
17. Which type of radiation gives off a high speed electrons from a neutron breaking apart? Beta
18. Which type of radiation has the highest energy radiation and occurs in an excited nucleus?
19. Rank Alpha, Beta and gamma radiation based on highest matter penetrating to lowest matter
penetrating.
20. The time required for one-half of the nuclei of a radioisotope sample to decay is called?
21. What is the difference between fission and fusion?
Potential Energy Diagrams
22. What is Av (Activation energy)?
23. Which letters are the reactants and which are the products?
24. Does the graph represent an endothermic or exothermic reaction?
25. How much energy is required to turn reactants into products?
26. What are the four factors that affect reaction rates?
27. What is a catalyst?
28. How does a catalyst affect the magnitude of the activation energy?
Indicators of a chemical RXN
29. Define the following terms: Physical Reaction, Chemical Reaction, Concentration, Surface
Area
30. What are the 4 indicators of a chemical RXN?
31. During the experiment, you combined a solution of calcium hydroxide and sodium hydroxide.
The new solution turned white with particles forming and falling to the bottom. There were to
bubbles created and no accurate temperature recording. Which indicators show the presence
of a chemical reaction in the experiment?
Balancing Chemical Equations
32. What is the Law of Conservation of matter state?
Balance the following chemical equations
33. __ KOH + __ H3PO4 → __ K3PO4 + __ H2O
34. __ SnO2 + __ H2 → __ Sn + __ H2O
Types of Chemical Reactions
35. What are the 6 different types of chemical reactions?
36. Which type of chemical reaction always produces CO2, H2O and energy?
37. If two elements combine to form one product, what type of reaction occurred?
38. In a reaction, you have one element reacting with one compound and producing a different
element and a different compound what type of reaction occured? (One element switched with
an element in the compound.)
Determine the type of chemical RXN that occurred
39. C10H8 + 12 O2 ---> 10 CO2 + 4 H2O
40. 8 Fe + S8 ---> 8 FeS
41. 2 H2O ---> 2 H2 + O2
42. Mg + 2 H2O ---> Mg(OH)2 + H2
43. Pb(NO3)2 + 2 KI ---> PbI2 + 2 KNO3
44. HBr + NaOH ---> NaBr + H2O
Stoichimoetry
45. What is the mole ratio of H2O to Ca(NO3)2 in the following equation?
2H3PO4 + 3Ca(OH)2 6H2O + Ca3PO4
46. In the reaction Ca + Cl2 → CaCl2, what is the mole ratio of chlorine to calcium chloride?
a. 2:3
c. 1:2 b. 2:1
d. 1:1
47. Calculate the molar mass of CuSO4.
48. Calculate the molar mass of Cr4(P2O7)3.
49. Find the empirical formula from the molecular formula. H8O8 
50. How many mole are in 50 grams of water?
51. How many molecules are in 50 moles of oxygen?
52. How many particles are in 50 g of H2O?
53. Balance the following equation:___NH3 + ___O2→ ___NO2 + ___H2O
The balanced equation shows that 1.00 mole of NH3requires ___ mole(s) of O2
a. 0.57
b. 1.25
c. 1.33
d. 1.75
e. 3.5
54. Find the percent composition of each element in the molecule
ammonium nitrate, NH4NO3
N=
H=
O=
55. A molecule with molecular weight of 180.18 g/mol is analyzed and found to contain 40.00%
carbon, 6.72% hydrogen and 53.28% oxygen.
What are the empirical and molecular formulas of the molecule?