Chemistry Reference
In-Depth Information
238
92
U
93
4.5
10
9
y
alpha particle emission
beta particle emission
92
234
90
91
Th
90
24.5 days
89
234
91
Pa
88
1.14 min
87
234
92
U
86
2.67
10
5
y
85
230
90
α
84
Th
8.3 × 10
4
y
83
82
226
88
Ra
81
206 210 214 218 222 226 230 234 238
1620 y
Mass number
222
86
Rn
(b)
3.82 days
Figure 21.1
Disintegration Series for Uranium-238
(a) The diagram shows the particle emitted and the half-life (Section 21.2) for each
event. (b) Atomic number is plotted versus mass number for each isotope in the
series diagrammed in part (a).
218
84
Po
3.05 min
214
82
Pb
Solution
26.8 min
237
Np
Because has a mass number that is 1 greater than an even multiple of 4,
the series is the
214
83
4
n
1
series:
Bi
237
4(59)
1
19.7 min
210
81
214
84
Practice Problem 21.3
What series involves
231
Th?
Tl
Po
1.5
10
4
s
1.32 min
EXAMPLE 21.4
210
82
Pb
22 y
Radium was discovered by Marie Curie (1867-1934) in pitchblende, a uranium
ore. Radium is produced from a series of disintegrations, starting with and
each producing an alpha particle or a beta particle (and possibly a gamma par-
ticle). Without looking at any figure or table, but using the mass number of
deduce how many alpha particles have been emitted from
238
92
U
210
83
Bi
4.85 days
226
88
Ra,
238
92
U
to pro-
210
84
duce this isotope of radium.
Po
138 days
Solution
206
82
The emission of an alpha particle lowers the mass number of the daughter iso-
tope by 4; the emission of a beta particle or a gamma particle produces no loss
Pb
(a)
