The document provides instructions for students to complete a block 3 training exercise involving: 1) Drawing Lewis structures for various molecules and determining their electron pair geometry and molecular geometry 2) Drawing resonance structures for polyatomic ions and identifying the best structure 3) Stating the hybridization of central atoms in various molecules and ions The document then lists specific molecules, ions, and questions for students to address relating to these topics.

1. Block 3 training exercises.
Draw the Lewis structures for each of the following molecules
and determine the electron pair
geometry and the molecular geometry as predicted by the
VSEPR.
1) F2
2) N2
3) ICL
4) CO2
5) NH3
6) CF4
7) C2H6
8) C2H4
9) C2H2
10) HCN
11) SO2
12) HNO3 (the hydrogen is bonded to one of the oxygens).
13) CH4O
For each of the following polyatomic ions, draw all resonance
structures. Based on the formal
charges identify which is the best resonance structure. (if all
resonance structures are equivalent
indicate so next to the structure). Indicate the bond angles as
predicted by VSEPR for the best

2. structure .
14) OH-
15) CN-
16) ClO2 –
17) ClO3 –
18) CO3 2-
19) SO3 2-
20) SCN-
21) HCO2-
22) NO2+
State the hybridization of each of the central atom in each of the
following.

3. 23) ClO2 –
24) ClO3 –
25) CO3 2-
26) SO3 2-
27) SCN-
28) HCO2-
29) NO2 -
30) Hydrogen Peroxide (H2O2) is a reactive molecule, often
used an antiseptic and sometimes
used for bleaching. Draw a Lewis structure for hydrogen
peroxide (peroxide is a
polyatomic ion). What is the oxidation state of the oxygen in
hydrogen peroxide?
Suggest a reason for its reactivity.
31) What is the hybridization of the central atom in Acetone
CH3COCH3?

4. 32) How many sigma bonds and how many pi bonds are in
Acetone?
33) Ozone (O3) is needed in the stratosphere to absorb (and
filter out) potentially damaging
ultraviolet light. However, in the lower atmosphere is a
dangerous pollutant as it is a very
reactive form of oxygen and as a result, very toxic and
destructive. Draw the two
reasonable structures, include formal charges. (Hint: it is not a
ring) Suggest a reason for
its high reactivity
34) Which of the following reactions is associated with the
lattice energy of Li2O (ΔH°latt)?
A) Li2O(s) → 2 Li⁺ (g) + O2⁻ (g)
B) 2 Li⁺ (aq) + O2⁻ (aq) → Li2O(s)
C) 2 Li⁺ (g) + O2⁻ (g) → Li2O(s)

5. D) Li2O(s) → 2 Li⁺ (aq) + O2⁻ (aq)
35). Which of the following reactions is associated with the
lattice energy of CaS (ΔH°latt)?
A) Ca(s) + S(s) → CaS(s)
B) CaS(s) → Ca(s) + S(s)
C) Ca2⁺ (aq) + S2⁻ (aq) → CaS(s)
D) Ca2⁺ (g) + S2⁻ (g) → CaS(s)
E) CaS(s) → Ca2⁺ (aq) + S2⁻ (aq)
36). Which of the following reactions is associated with the
lattice energy of RbI (ΔH°latt)?
A) Rb(s) +
2
1
I2(g) → RbI(s)
B) RbI(s) → Rb⁺ (g) + I⁻ (g)
C) RbI(s) → Rb(s) +
2
1
I2(g)
D) RbI(s) → Rb⁺ (aq) + I⁻ (aq)
E) Rb⁺ (g) + I⁻ (g) → RbI(s)

6. 37). Which of the following NaCl, KCl, LiCl, CsCl has the
highest magnitude of lattice energy?
38). Identify the compound with the lowest magnitude of lattice
energy among the following:
KCl, KBr,SrO,CaO.
39). Identify the shortest bond.
A) single covalent bond
B) double covalent bond
C) triple covalent bond
D) all of the above bonds are the same length
40). Identify the weakest bond.
A) single covalent bond
B) double covalent bond
C) triple covalent bond
D) all of the above bonds are the same strength
41). Identify the number of bonding pairs and lone pairs of
electrons in water.
A) 1 bonding pair and 1 lone pair
B) 1 bonding pair and 2 lone pairs
C) 2 bonding pairs and 2 lone pairs
D) 2 bonding pairs and 1 lone pair
E) 3 bonding pairs and 2 lone pairs

7. 42) Write the best Lewis structure for OCl2.
43) Choose the best Lewis structure for ICl5.
A)
B)
C)
D)
E)
44) Choose the best Lewis structure for SF4.
A)
B)
C)

8. D)
E)
45). Choose the best Lewis structure for SeO42⁻ .
A)
B)
C)
D)
E)
46). Which of the following processes are exothermic?
A) Cl2(g) → 2Cl(g)
B) Br(g) + e⁻ → Br⁻ (g)
C) Li(s) → Li(g)
D) NaF(s) → Na⁺ (g) + F⁻ (g)
E) None of the above are exothermic.

9. 47) Which of the following processes are exothermic?
A) the second ionization energy of Mg
B) the sublimation of Li
C) the breaking the bond of I2
D) the formation of NaBr from its constituent elements in their
standard state
E) None of the above are exothermic
48). Use the bond energies provided to estimate ΔH°rxn for the
reaction below.
PCl3(g) + Cl2(g) → PCl5(l) ΔH°rxn = ?
Bond Bond Energy (kJ/mol)
Cl-Cl 243
P-Cl 331
49) Use the bond energies provided to estimate ΔH°rxn for the
reaction below.
2 Br2(l) + C2H2(g) → C2H2Br4(l) ΔH°rxn = ?
Bond Bond Energy (kJ/mol)
Br-Br 193
C≡C 837
C-C 347
C-Br 276
C-H 414

10. 50) Use the bond energies provided to estimate ΔH°rxn for the
reaction below.
CH3OH(l) + 2 O2(g) → CO2(g) + 2 H2O(g) ΔH°rxn = ?
Bond Bond Energy (kJ/mol)
C-H 414
C-O 360
C=O 799
O=O 498
O-H 464
51 ) Determine the electron geometry (eg) and molecular
geometry (mg) of NCl3.
52) Determine the electron geometry (eg) and molecular
geometry (mg) of BrF3.
53) Determine the electron geometry (eg) and molecular
geometry (mg) of ICl2⁻ .
54) Determine the electron geometr y (eg) and molecular
geometry (mg) of XeF2.
55) Consider the molecule below. Determine the molecular
geometry at each of the 2 labeled
carbons.

11. 56) Consider the molecule below. Determine the molecular
geometry at each of the 3 labeled
atoms.
57). Determine the electron geometry (eg), molecular geometry
(mg), and polarity of SO2.
58) Determine the electron geometry, molecular geometry and
polarity of SF6 .
59) Describe a pi bond.
60) Which of the following best describes a sigma bond.
A) side by side overlap of p orbitals
B) end to end overlap of p orbitals
C) s orbital overlapping with the side of a p orbital
D) overlap of two s orbitals
E) p orbital overlapping with a d orbital
61) Fill in the black with the appropriate word. A molecule
containing a central atom with sp
hybridization has a(n) __________ electron geometry.

12. 62) How many electron groups around a molecule with sp
hybridization.
63) Draw the Lewis structure for BrO4⁻ . What is the
hybridization on the Br atom?
64) Draw the Lewis structure for SF6. What is the
hybridization on the S atom?
65) Draw the Lewis structure for BrF5. What is the
hybridization on the Br atom?
66) How many of the following molecules have sp3
hybridization on the central atom?
XeCl4 CH4 SF4 C2H2
67). Use the molecular orbital diagram shown to determine
which of the following is most stable.
68) Use the molecular orbital diagram shown to determine
which of the following are
paramagnetic.

13. 69) Use the molecular orbital diagram shown to determine
which of the following are
paramagnetic.
70). Use molecular orbital theory calculate the bond order of N2
+
71). Use molecular orbital theory calculate the bond order of C2
–
72). Use molecular orbital theory calculate the bond order of O2
+
73). Based on molecular orbital theory which is more stable O2
or O2+
74). Based on molecular orbital theory which is more stable N2
or N2+
75). Based on molecular orbital theory which is more stable C2
or C2-
76). A
Solution

14. is prepared by dissolving 165 g of NaCl in 1000 ml of water.
This solution was
labelled stock solution. Once the solution was prepared 200.00
ml sample of the solution was
transferred into a 500.ml volumetric flask and diluted to the
mark with water. Following 125 ml
of this solution was transferred to a 200 ml volumetric flak and
it was diluted to the mark with
water. What is the concentration of the last solution?
77). Imagine 100.0 ml of a 0.767 M of a sulfate solution was
prepared by diluting 38.0 ml of a
stock solution to 100.ml with water. What is the concentration
of the original solution?
78) Household hydrogen peroxide is an aqueous solution
containing 3.0% hydrogen peroxide by
mass. What is the molarity of the solution? (assume density of
the solution 1.01 g/mL.)

15. 79). The Density of Nitric acid is 1.41 g/mL. Giving that Nitric
Acid is 70.3%. by mass HNO3 in a
concentrated form that is 70.3% n
How much of the concentrated acid will be needed in order to
make 1.15L of a 0.100M solution
of HNO3?
80) Which of the following reactions is associated with the
lattice energy of Li2O (ΔH°latt)?
A) Li2O(s) → 2 Li⁺ (g) + O2⁻ (g)
B) 2 Li⁺ (aq) + O2⁻ (aq) → Li2O(s)
C) 2 Li⁺ (g) + O2⁻ (g) → Li2O(s)
D) Li2O(s) → 2 Li⁺ (aq) + O2⁻ (aq)
E) 2 Li(s) +
2
1
O2(g) → Li2O(s)

16. 81) Which of the following reactions is associated with the
lattice energy of CaS (ΔH°latt)?
A) Ca(s) + S(s) → CaS(s)
B) CaS(s) → Ca(s) + S(s)
C) Ca2⁺ (aq) + S2⁻ (aq) → CaS(s)
D) Ca2⁺ (g) + S2⁻ (g) → CaS(s)
E) CaS(s) → Ca2⁺ (aq) + S2⁻ (aq)
82) Which of the following reactions is associated with the
lattice energy of RbI (ΔH°latt)?
A) Rb(s) +
2
1
I2(g) → RbI(s)
B) RbI(s) → Rb⁺ (g) + I⁻ (g)

17. C) RbI(s) → Rb(s) +
2
1
I2(g)
D) RbI(s) → Rb⁺ (aq) + I⁻ (aq)
E) Rb⁺ (g) + I⁻ (g) → RbI(s)
83) Identify the compound with the highest magnitude of lattice
energy.
A) NaCl
B) KCl
C) LiCl
D) CsCl
84) Identify the compound with the lowest magnitude of lattice
energy.
A) KCl

18. B) KBr
C) SrO
D) CaO
85) Place the following in order of decreasing magnitude of
lattice energy.
K2O Rb2S Li2O
Draw the Lewis structures for each of the following molecules
and determine the electron pair geometry and the molecular
geometry as predicted by the VSEPR.For each of the following
polyatomic ions, draw all resonance structures. Based on the
formal charges identify which is the best resonance structure.
(if all resonance structures are equivalent indicate so next to the
structure). Indicate the bond ...State the hybridization of each
of the central atom in each of the following.