Chapter 7 Assignment Answers
31. a. 1 gained
b. 1 lost
c. 3 gained
d. 2 lost
e. 1 lost
f. 1 gained
33. Valence electrons are electrons found in the highest energy level
(shell) of an atom.
34. a. 7 e- ; group VA
d. 56 e- ; group IIA
b. 3 e- ; group IA
c. 15 e- ; group VA
e. 35 e- ; group VIIA f. 6 e- ; group IVA
35. a.
b.
c.
d.
36. a. 2
b. 3
c. 1
d. 2
37. a. Al+3
B. Li+1
c. Ba+2
d. K+1
e. Ca+2
f. Sr+2
38. Nonmetals form anions because of their high electronegativity
values. They will gain the necessary number of electrons to
complete their octet.
39. a. S -2
b. Na+1
c. F-1
d. P-3
40. a. 3 e-
b. 2 e-
c. 1 e-
d. 3 e-
41. Ionic compounds tend to form when metals react with nonmetals.
This is because these classes of elements have a large difference in
electronegativity, which will result in an electron transfer. So, the
answer is a, c, e.
44. a, b, and d.
46. Ionic substances are brittle because like-charged ions can be forced
together with a hammer blow, resulting in violent repulsive forces
that shatter the crystal.
47. Molten MgCl2 contains freely-moving ions that carry the electrical
current. The solid form of MgCl2 contains ions that are locked in
place and cannot carry an electric current.
48. Metals are good conductors of electricity because they have freelymoving valence electrons on their surface.
51. Steel is an alloy, and there are different alloys of steel – each one is
different in chemical composition. The properties of each alloy are
dependent on the chemical composition.
53. a.
58. a. [Ar]3d6
b.
c.
b. [Ar]3d7
d.
e.
f.
c. [Ar]3d8
62. a, b, c, and d all have the same electron configuration: [Ne]3s23p6.
This is the stable configuration of a noble gas, Argon.
66. Ionic compounds are composed of the correct ratio of anions and
cations – this ratio balances the charges to zero net charge.
67. a, c, e and f.
78. Metals are ductile (can be drawn into thin wires) and malleable
(can be hammered and bent into shapes without snapping or breaking).
These changes are possible because a metal consists of metal cations in
a sea of valence electrons. When subjected to pressure, the cations
easily slide past one another, and we see this on a macroscopic scale as
the metal bending and taking on different shapes. The sea of valence
electrons acts as a sort of “buffer” for the metal cations, and allows
them to slide around. The top of page 202 gives a nice description of
this.