Page 7 - Academic Press Encyclopedia of Physical Science and Technology 3rd InOrganic Chemistry

P1: FYK Revised Pages
Encyclopedia of Physical Science and Technology EN001F-11 May 7, 2001 12:19

Actinide Elements 215

TABLE I Discovery or Synthesis of Actinide Elements
Most
Atomic Source or Isotope first stable
number Element Symbol Investigators synthesis discovered isotope Source of name
89 Actinium Ac A. Debierne (1899) Uranium ore 227 Ac 227 Ac Greek word for ray
90 Thorium Th J. J. Berzelius (1828) Thorium ore 232 Th 232 Th Scandinavian god of
war, Thor
91 Protactinium Pa K. Fajans, O. G¨ohring Uranium ore 234 Pa 234 Pa Parent of actinium
(1913) concentrates
92 Uranium U M. H. Klaproth (1789) Pitchblende 238 U 238 U Planet Uranus
93 Neptunium Np E. M. McMillan, Bombardment of 239 Np 237 Np Planet Neptune
P. Abelson (1940) uranium with
neutrons:
238 1
92 U + n →
0
−β −
239 239 Np
92 U −−→ 93
23 min
94 Plutonium Pu G. T. Seaborg, Bombardment of 238 Pu 244 Pu Planet Pluto
E. M. McMillan, uranium with
J. W. Kennedy, deuterons:
2
A. Wahl (1940) 238 U + H →
92
1
1 238
2 n + 93 Np
0
−β − 238
−−−→ 94 Pu
2.1 days
95 Americium Am G. T. Seaborg, Bombardment of 241 Am 243 Am America
R. A. James, plutonium with
L. O. Morgan, neutrons:
1
A. Ghiorso (1944) 239 Pu + 2 n →
94
0
241 −β − 241 Am
94 Pu −→ 95
96 Curium Cm G. T. Seaborg, Bombardment of 242 Cm 247 Cm Pierre and Marie Curie
R. A. James, plutonium with
A. Ghiorso (1944) helium ions:
239 4
94 Pu + He →
2
242 Cm + n
1
96 0
97 Berkelium Bk S. G. Thompson, Bombardment of 243 Bk 247 Bk Berkeley, CA
A. Ghiorso, americium with
G. T. Seaborg (1949) helium ions:
4
241 Am + He
95 2
243 1
→ 97 Bk + 2 n
0
98 Californium Cf S. G. Thompson, Bombardment of 245 Cf 251 Cf California
K. Street, A. Ghiorso, curium with
G. T. Seaborg (1950) helium ions:
4
242 Cm + He
96 2
245 1
→ 98 Cf + n
0
99 Einsteinium Es Workers at Berkeley, Discovered in the 253 Es 252 Es Albert Einstein
Argonne, and fallout of the first
Los Alamos (1952) thermonuclear
explosion as a
result of uranium
bombardment
with fast neutrons:
238 1
92 U + 15 n →
0
−7β −
253 253 Es
92 U −→ 99
Continues