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Element 61 - Promethium (Pm)
After Prometheus; discovered 1947; the only rare earth that has never been found in nature. Produced in nuclear reactors, radioactive promethium in an "atomic battery" no bigger than a drawing pin powers guided-missile instruments, watches, and radios.
Properties
Atomic Number
:
61
Atomic Weight
:
(145)
Electron Configuration
(at ground state):
1s
2
2s
2
2p
6
3s
2
3p
6
3d
10
4s
2
4p
6
4d
10
4f
5
5s
2
5p
6
6s
2
Oxidation States
(Bold most stable):
+3
Boiling Point
(K):
3273
Melting Point (K):
1315
Density
(at 300K -- g/cm
3
):
7.22
Atomic Volume (at 300K -- cm
3
/mol)
22.4
Mass Number
(Bold naturally occurring) --
Half-Life
--
Disintigration Type
:
145 -- 18 years -- orbital
electron capture
147 -- 2.62 years --
beta particle
(
electron
) emission
Covalent Radius (Å):
1.63
First
Ionization Potential
(V):
5.55
Electronegativity
(Pauling's):
1.13
Electrical Conductivity (at 293K for polycrystalline material -- 10
6
-1
cm
-1
):
2
Thermal Conductivity (at 300K -- W m
-1
K
-1
):
17.9
Crystal Structure:
Hexagonal
Acid
-
Base
Properties:
Very basic