Chemistry Reference
In-Depth Information
2.00
10
10
m
13.53 Why is the polarity of the covalent bonds in of
little interest, compared with that in a covalent molecule
such as
13.54
(a) The molecule, where A is one element and X is
another element with a significantly different elec-
tronegativity, has no dipole. What is its geometry?
(b) The molecule, where Z is one element and X is
another element with a significantly different elec-
tronegativity, has a finite dipole. What is its probable
geometry?
13.55 Determine the shape of (a) the
Na
2
SO
3
lattice, about
apart. (See Problem
13.59.)
13.62
Which anion in Figure 13.2, when compared with its
parent atom, has had the greatest percentage increase in
radius in acquiring the extra electron(s)?
13.63 Calculate the difference between the ionization energy
of lithium and the electron affinity of bromine. Deduce
whether the transfer of an electron from one to the other
in the gas phase is spontaneous.
13.64 Without looking at Figure 5.4, deduce the bond type
(ionic, polar covalent, nonpolar covalent) in each of the
following:
(a) (b) (c)
13.65 Calculate the difference between the sum of the first two
ionization energies of magnesium and the sum of the first
two electron affinities of oxygen. Deduce whether the
transfer of two electrons from one to the other in the gas
phase is spontaneous. (The second electron affinity of
oxygen is
13.66
Plot the normal boiling points of
and versus the atomic number
of the central atom. Extrapolate the line to atomic num-
ber 8, for Predict the normal boiling point that wa-
ter would have if it were not for its hydrogen bonding.
13.67
The hydrogen bonding in water seems to raise the boil-
ing point from that expected if there were no hydrogen
bonding
SO
3
?
AX
3
ZX
3
SOCl
2
molecule and
(b) the molecule.
13.56
Determine the shape of (a) the
H
2
SO
4
O
2
N
¬
NO
2
molecule
SeCl
2
CO
2
AlBr
3
and (b) the HOOH molecule.
13.57 Determine the bond angles around each nitrogen atom in
(a) the
HN
“
NH
molecule and (b) the
NH
2
¬
NH
2
molecule.
13.58 Consider the size of Is it qualitatively any different
from the size of every other cation? Would you expect
such an ion to attract electrons well or poorly?
13.59
The force of attraction between oppositely charged ions
varies inversely as the square of the distance between
them:
H
.
816 kJ/mol.)
H
2
S
(
60.7°C),
H
2
Se
(
42°C),
H
2
Te
(
2°C)
H
2
O.
k
d
2
f
1
2
to 2 times more than the hydrogen bonding in
2.0
10
10
m
Ions in a solid might be at a distance about
apart. If a pair of ions is separated to twice the distance in
the solid, what percentage of the force of attraction
remains? If they are separated to the average distance
between gas molecules (say
HF or
NH
3
.
(See Problem 13.66.) Give a possible
explanation.
13.68
Draw representations of the four bases of Figure 13.13,
with the covalent bond (to the rest of the DNA) pointing
up. Also draw their mirror images, as shown below for
guanine (G). See if any combination other than G with C
or A with T would be as effective in hydrogen bonding to
hold the strands of DNA together.
10
9
m),
3
how much
force is expected to remain?
13.60 If two ions are separated to a distance 10 times their
normal separation, what happens to their normal force of
attraction?
13.61
(a) Calculate the average volume occupied by one gas
molecule at STP.
(b) Assuming that each molecule occupies a cube with
that volume, calculate the length of each edge of the
cube. That is the average distance between mole-
cules in this sample of gas.
(c) Compare the attraction of two monatomic ions at
this distance with that of the same two ions in a solid
—
N
—
—
—
H
H
N
—
N
—
—
—
H
H
N
—
—
O
O
(mirror image)
G
G
