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Element 89 - Actinium (Ac)
From
aktinos
, or ray; discovered 1899. Second rarest of the elements. Found in pitchblende.
Properties
Atomic Number
:
89
Atomic Weight
:
(227)
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
6s
2
6p
6
6d
1
7s
2
Oxidation States
(Bold most stable):
+3
Boiling Point
(K):
3470
Melting Point (K):
1324
Density
(at 300K -- g/cm
3
):
10.07
Atomic Volume (at 300K -- cm
3
/mol)
22.5
Number of natural
radioactive
isotopes:
2
Mass Number
(Bold naturally occurring) --
Half-Life
--
Disintigration Type
:
227
-- 21.77 years --
beta particle
(
electron
) emission
Atomic Radius (Å):
1.88
First
Ionization Potential
(V):
5.17
Electronegativity
(Pauling's):
1.1
Specific Heat
Capacity (at 300K -- J g
-1
K
-1
):
0.120
Thermal Conductivity (at 300K -- W m
-1
K
-1
):
12
Crystal Structure:
Cubic, face centered