Cobalt

Symbol CoAtomic number 27
Atomic mass
58.9332
Thermal conductivity
1.00
Atomic radius
1.67
Covalent radius
1.16
Density
8.90
Atomic volume
6.7
Melting point
1768
Oxidation states
2,3
Boiling point
3143
Stable isotopes
1
Heat of vapor.
376.50
Electronegativity
1.88
Heat of fusion
16.190
First ionization
7.86
Specific heat
0.42
Electrical conduct.
...
Electron configuration

General descriptionNuclear data
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Periodic Table

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Cobalt

Cobalt is a silvery-white metal, with a slight reddish tinge. It occurs in the minerals smaltite and safflorite with the composition CoAs2. Cobalt also forms an arsenide with the content CoAs2-3 which is called skutterudite. The sulfide mineral cobaltite, CoAsS, also occurs. Cobalt is usually found in association with nickel. Cobalt forms the sulfide mineral linnaeite, Co3S4. Copper, cobalt and nickel join in the sulfide carrollite, Cu(Co,Ni)2S4. Cobalt joins with iron and arsenic in the sulfide glaucodot, (Co,Fe)AsS. Cobalt and nickel form the sulfide siegenite, CoNi2S4. Roselite is an arsenate that contains cobalt, magnesium and calcium and forms red crystals. Erythrite is an arsenate of cobalt and also shows a red or rose color.

Cobalt is used to produce the strongly ferromagnetic alloy alnico which is used to make strong permanent magnets. Alnico alloys iron, nickel, cobalt and aluminum.

Cobalt chloride (CoCl2.6H2O) forms red crystals which turn blue when dehydrated. Cobalt oxide, CoO, is a black powder, but it gives a blue color to glass when dissolved in it (cobalt glass).

Atomic dataNuclear data
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Periodic Table

Chemistry concepts

Reference
Pauling
Ch. 27
 
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Cobalt Nuclear Data

Z
A
Atomic
Mass (u)
Nuclear
Mass(GeV/c2
Binding
Energy(MeV)
Spin
Natural
Abund.
Half-life
Decay
Q
MeV
27
56
55.939841
52.0943
486.92
4
...
77.7d
b+
4.57
27
57
56.936294
53.0225
498.29
7/2
...
271d
EC
0.84
27
59
58.933198
54.8826
517.32
7/2
1.00
stable
...
...
27
60
59.933820
55.8147
524.81
5
...
5.272y
b-
2.82

The decay of cobalt-57 by electron capture produces an excited state of iron-57 which emits gamma rays to reach its ground state. One of those transitions has become very important for Mossbauer effect studies.

Atomic data
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Periodic Table

Chemistry concepts

Reference
Rohlf
 
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