Chemistry Reference
In-Depth Information
hols and ethers can be isomers of each other, as can aldehydes
and ketones, and also organic acids and esters.
21.2
The symbol U stands for the naturally occurring mixture of
isotopes of uranium; stands for only one isotope and rep-
resents the nucleus, rather than the entire atom.
238
U
20.60
R
W
H
W
R
W
H
W
R
W
H
W
R
W
H
W
R
W
H
W
R
W
H
W
21.3
(a)
is a electron; is a positron.
(b)
The is a positron—a positively charged electron.
(c)
There is no difference.
b
b
UC±C±C±C±C±C±C±C±C±C±C±CU
b
H
H
H
H
H
H
H
H
H
H
H
H
21.4
The atomic numbers, which are the subscripts, appear in the
periodic table. The superscripts—the mass numbers—are not
generally given there. (Mass numbers for the few elements
that do not occur naturally are given in parentheses in most
periodic tables.) The atomic mass given in a periodic table can
give a clue to the mass number of the most abundant isotope
for many but not all elements. For example, the atomic mass
of bromine is almost exactly 80, but the two isotopes that
form the naturally occurring mixture have mass numbers 79
and 81. (They occur in almost a 1:1 ratio.)
(Each R stands for C
6
H
5
.)
20.62
Gases have little intermolecular forces between their molecules.
The molecules of polymers are very large, and intermolecular
forces, even in nonpolar polymers, are considerable. We do not
expect polymers to be gases under the conditions given.
20.65
An amino acid has both an amine group and an acid group in
the same molecule; an amide is the product of the reaction of
separate molecules having those two groups:
NH
2
CH
2
COOH
CH
3
CONHCH
3
1
1
H (proton)
2
1
H (deuteron)
21.5
(a)
(b)
An amino acid
An amide
3
1
H (tritium nucleus)
0
1
b (positron)
(c)
(d)
20.69
0
1
e (electron) or
0
1
b (beta particle)
(e)
(f )
(g)
±CH
2
±
4
2
He (alpha particle)
1
0
n (neutron)
0
0
g
(gamma particle)
(h)
20.73 (a)
, 0, , 0
(b)
The carbon atoms in isomers have the
same oxidation number.
20.74 (a)
2
2
21.6
Parent isotope
92
91
90
89
88
87
86
85
84
83
82
81
H
W
3
2
2
3
Cl±
±C±
±Cl
4
1
1
4
1
W
W
W
C
W
Cl
5
6
6
5
2
Cl±±Cl
1,1-Di(4-chlorophenyl)-2,2,2-trichloroethane
(b)
Cl
Cl
H
W
3
3
2
2
±C±
alpha particle emission
beta particle emission
4
1
1
4
H
5
6
6
5
Di(2-chlorophenyl)methane
20.77
1,1-Dichloroethene
20.79
Aldehydes and acids do not need positional numbers for their
functional groups. In these compounds, the functional groups
are always at the end of the carbon chain. (Esters and amides
do not need positional numbers for the carbon chain of the
acid part but might need them for the other part.)
20.84
A fully hydrogenated fat is a saturated fat, whether it started
out unsaturated or not. Do not pay extra for it.
20.89
1,2-;
207
211 215 219 223 227 231 235
Mass number
21.7
The
chemical
properties are the same; only the
nuclear
prop-
erties differ.
21.8
The
nuclear
reactions are dangerous.
21.9
When half of the sample has disintegrated, the rate of disinte-
gration is half of what it was before, and only half of what is
left will disintegrate in the next 2.00 years.
21.10
The mass will be approximately 0.100 g, with 0.050 g of
remaining, a tiny mass of beta particles produced, and almost
all the rest Only a tiny fraction of the original mass has
been transformed into energy, with mass that has escaped
from the system.
21.11
Only the series has an isotope with half-life as much
as 7% of that of the original parent. The other series have no
isotope nearly that close.
21.12 (a)
Fusion
1,3-;
1,4-;
1,5-;
1,6-;
1,7-;
1,8-;
2,3-;
2,6-;
2,7-
NH
3
CH
2
COO
20.90
207
TI
2
1
20.92
CH
3
OCHCH
3
CH
3
207
Pb.
3
20.93
H
2
C
“
CH
¬
CH
“
CH
2
4
n
1
Diene means two double bonds.
21 Nuclear Reactions
21.1
(b)
Spontaneous
(c)
Fission
(d)
None
21.13 (a)
There is no difference. All four are representations for an al-
pha particle (a helium nucleus).
1.25
10
9
1.25
10
9
(c)
6.25
10
8
(b)
