Cobalt

27
Co
Group
9
Period
4
Block
d
Protons
Electrons
Neutrons
27
27
32
General Properties
Atomic Number
27
Atomic Weight
58.933195
Mass Number
59
Category
Transition metals
Color
Gray
Radioactive
No
From the German word Kobald, goblin or evil spirit; also from the Greek cobalos, mine
Crystal Structure
Simple Hexagonal
History
Cobalt compounds have been used for centuries to impart a rich blue color to glass, glazes and ceramics.

The element was first isolated by Swedish chemist George Brandt in 1735.

He showed it was the presence of the element cobalt that caused the blue color in glass, not bismuth as previously thought.
Electrons per shell
2, 8, 15, 2
Electron Configuration
[Ar] 3d7 4s2
Co
Supplemental colbalt is essential in sheep's diets to improve the wools quality
Physical Properties
Phase
Solid
Density
8.86 g/cm3
Melting Point
1768.15 K | 1495 °C | 2723 °F
Boiling Point
3200.15 K | 2927 °C | 5300.6 °F
Heat of Fusion
16.2 kJ/mol
Heat of Vaporization
375 kJ/mol
Specific Heat Capacity
0.421 J/g·K
Abundance in Earth's crust
0.003%
Abundance in Universe
0.0003%
Pure
Image Credits: Wikimedia Commons (Alchemist-hp)
Pure cobalt chips, electrolytically refined, as well as a high purity cobalt cube for comparison
CAS Number
7440-48-4
PubChem CID Number
104730
Atomic Properties
Atomic Radius
125 pm
Covalent Radius
126 pm
Electronegativity
1.88 (Pauling scale)
Ionization Potential
7.881 eV
Atomic Volume
6.7 cm3/mol
Thermal Conductivity
1 W/cm·K
Oxidation States
-1, 1, 2, 3, 4, 5
Applications
Cobalt is used in the preparation of magnetic, wear-resistant and high-strength alloys.

Cobalt is widely used in batteries and in electroplating.

Radioactive 60Co is used in the treatment of cancer.

A solution of the chloride is used as a sympathetic ink.
Cobalt and its compounds are considered to be slightly toxic
Isotopes
Stable Isotopes
59Co
Unstable Isotopes
47Co, 48Co, 49Co, 50Co, 51Co, 52Co, 53Co, 54Co, 55Co, 56Co, 57Co, 58Co, 60Co, 61Co, 62Co, 63Co, 64Co, 65Co, 66Co, 67Co, 68Co, 69Co, 70Co, 71Co, 72Co, 73Co, 74Co, 75Co