The electron configuration: 1s22s22p63s23p64s23d 7

1
The electron configuration 1s22s22p63s23p64s23d
7 is consistent with which atom?

• Fe
• Co
• Cu
• Ni

2
Correct Answer
The electron configuration Ar4s23d 7
corresponds to cobalt.

• Fe
• Co
• Cu
• Ni

3
The electron configuration of Fe3 is which of
the following?

• 1s22s22p63s23p64s23d6
• 1s22s22p63s23p64s23d3
• 1s22s22p63s23p63d5
• 1s22s22p63s23p64s13d4

4
Correct Answer

• 1s22s22p53s23p64s23d6
• 1s22s22p53s23p64s23d3
• 1s22s22p53s23p63d5
• 1s22s22p53s23p64s13d4

5
Arrange the following ionic compounds in order of
increasing lattice energy LiCl, NaCl, MgCl2

• NaCl lt LiCl lt MgCl2
• LiCl lt NaCl lt MgCl2
• MgCl2 lt NaCl lt LiCl

6
Correct Answer
Lattice energy depends on size of the ions and
their charges. MgCl2 has the highest lattice
energy because it has a more positive cation.
LiCl is higher than NaCl because the interatomic
distance between cation and ion is shorter.

• NaCl lt LiCl lt MgCl2
• LiCl lt NaCl lt MgCl2
• MgCl2 lt NaCl lt LiCl

7
Which of the following carboncarbon atom bonds
would be expected to be the shortest?

• C?C
• C?C
• C?C

8
Correct Answer
The bond length decreases as the bond enthalpy
increases in general, as the number of bonds
between two atoms increases, the bond grows
shorter and stronger.

• C?C
• C?C
• C?C

9
Based on the electronegativities of the atoms,
which of the following bonds would you predict is
most polar?

• C?C
• C?N
• C?O
• C?Si
• C?Br

10
Correct Answer
The difference in electronegativities is greatest
between O (3.5) and C (2.5) for a net difference
of 1.0. Each of the other combinations yields a
smaller value for electronegativity difference.

• C?C
• C?N
• C?O
• C?Si
• C?Br

11
Boron (B) has an electronegativity of 2.0
chlorine (Cl) has an electronegativity of 3.0.
Which of the following BEST describes a B?Cl
bond?

• Ionic
• Polar covalent
• Nonpolar covalent

12
Correct Answer
The difference in electronegativities is 1.0
because Cl 3.0 and B 2.0. This is too low to
be an ionic bond but too high to be a nonpolar
covalent bond.

• Ionic
• Polar covalent
• Nonpolar covalent

13
Which of the following BEST describes the formal
charges on the atoms in the cyanide ion, CN? ?

• C 1, N ?1
• C ?1, N 1
• C 0, N ?1
• C ?1, N 0

14
Correct Answer
The formal charges are calculated from the
difference between number of valence electrons
and number of electrons assigned to each atom in
the Lewis structure, thus C 4 valence e? ? 5
e? ? 1 N 5 valence e? ? 5 e? 0

• C 1, N ?1
• C ?1, N 1
• C 0, N ?1
• C ?1, N 0

15
Which is predicted to have the longest
carbonoxygen bonds CO, CO2, or CO32??

• CO32?
• CO2
• CO

16
Correct Answer
In CO, the carbonoxygen bond is a triple bond,
while in CO2 both carbonoxygen bonds are double
bonds. In CO32?, there are three resonance
structures and the average carbonoxygen bond is
1 1/3.

• CO32?
• CO2
• CO

17
Calculate DH from the following bond enthalpies
for the reaction
2 NCl3 ? N2 3 Cl2
D(N?Cl) 200, D(N?N) 941, D(Cl?Cl) 242 (all
kJ/mol).

• ?467 kJ
• 467 kJ
• 17 kJ
• ?983 kJ

18
Correct Answer
DH S(bond enthalpies of bonds broken) ? S (
bond enthalpies of bonds formed) DH 6(200) ?
941 3(242) DH 1200 ? (1667) DH ? 467

• ?467 kJ
• 467 kJ
• 17 kJ
• ?983 kJ