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Element 99 - Einsteinium (Es)
After Albert Einstein; discovered 1952. It was first detected in the debris from a 1952 H-bomb explosion in the Pacific after tons of radioactive coral from atolls in the blast area were sifted and examined. The element was later made in a nuclear reactor.
Properties
Atomic Number
:
99
Atomic Weight
:
(252)
Electron Configuration
(at ground state):
1s
2
2s
2
2p
6
3s
2
3p
6
3d
10
4s
2
4p
6
4d
10
5s
2
5p
6
4f
14
5d
10
5f
11
6s
2
6p
6
7s
2
Oxidation States
(Bold most stable):
+3
Melting Point (K):
1130
Mass Number
(Bold naturally occurring) --
Half-Life
--
Disintigration Type
:
252 -- 472 days --
alpha particle
emission
253 -- 20.47 days --
alpha particle
emission
254 -- 276 days --
alpha particle
emission
First
Ionization Potential
(V):
6.42
Electronegativity
(Pauling's):
1.3
Thermal Conductivity (at 300K -- W m
-1
K
-1
):
10