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Element 37 - Rubidium (Rb)
From
rubidus
, or red (the color its salts impart to flames); discovered 1861. Rubidium, used in electric-eye cells, is also a potential space fuel. Like potassium, it is slightly radioactive, and has been used to locate brain tumors, as it collects in tumors but not in normal tissue.
Properties
Atomic Number
:
37
Atomic Weight
:
85.4678
Electron Configuration
(at ground state):
1s
2
2s
2
2p
6
3s
2
3p
6
3d
10
4s
2
4p
6
5s
1
Oxidation States
(Bold most stable):
+1
Boiling Point
(K):
961
Melting Point (K):
312.63
Density
(at 300K -- g/cm
3
):
1.532
Atomic Volume (at 300K -- cm
3
/mol)
55.9
Number of stable
isotopes
:
1
Number of natural
radioactive
isotopes:
1
Mass Number
(Bold naturally occurring) --
Half-Life
--
Disintigration Type
:
86 -- 18.7 days --
beta particle
(
electron
) emission
87
-- 4.8 x 10
11
years --
beta particle
(
electron
) emission
Covalent Radius (Å):
2.16
Atomic Radius (Å):
2.48
First
Ionization Potential
(V):
4.177
Electronegativity
(Pauling's):
0.82
Specific Heat
Capacity (at 300K -- J g
-1
K
-1
):
0.363
Heat of Vaporization (kJ/mol):
69.2
Heat of Fusion (kJ/mol):
2.34
Electrical Conductivity (at 293K for polycrystalline material -- 10
6
-1
cm
-1
):
47.8
Thermal Conductivity (at 300K -- W m
-1
K
-1
):
58.2
Crystal Structure:
Cubic, body centered
Acid
-
Base
Properties:
Very basic