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Element 75 - Rhenium (Re)
From the Rhine provinces of Germany; discovered 1925. Rhenium is the ninth scarcest element and has the second highest melting point. It is used in "thermocouples" (electric thermometers for measuring high temperatures) and in the contact points of electrical switches.
Properties
Atomic Number
:
75
Atomic Weight
:
186.207
Electron Configuration
(at ground state):
1s
2
2s
2
2p
6
3s
2
3p
6
3d
10
4s
2
4p
6
4d
10
4f
14
5s
2
5p
6
5d
5
6s
2
Oxidation States
(Bold most stable):
+7
, +6,
+4
, +2, -1
Boiling Point
(K):
5870
Melting Point (K):
3455
Density
(at 300K -- g/cm
3
):
21.0
Atomic Volume (at 300K -- cm
3
/mol)
8.85
Number of stable
isotopes
:
1
Number of natural
radioactive
isotopes:
1
Mass Number
(Bold naturally occurring) --
Half-Life
--
Disintigration Type
:
187
-- 5 x 10
10
years --
beta particle
(
electron
) emission
Covalent Radius (Å):
1.28
Atomic Radius (Å):
1.37
First
Ionization Potential
(V):
7.88
Electronegativity
(Pauling's):
1.9
Specific Heat
Capacity (at 300K -- J g
-1
K
-1
):
0.137
Heat of Vaporization (kJ/mol):
707.1
Heat of Fusion (kJ/mol):
33.05
Electrical Conductivity (at 293K for polycrystalline material -- 10
6
-1
cm
-1
):
5.8
Thermal Conductivity (at 300K -- W m
-1
K
-1
):
47.9
Crystal Structure:
Hexagonal
Acid
-
Base
Properties:
Slightly acidic