Cobalt

Cobalt (Co)

Light grey transition element. Some meteorites contain small amounts of metallic cobalt. Generally alloyed for use. Mammals require small amounts of cobalt salts. Cobalt-60, an artificially produced radioactive isotope of Cobalt is an important radioactive tracer and cancer-treatment agent. Discovered by G. Brandt in 1737.
Atomic Number27
Atomic Weight58.933194
Mass Number59
Group9
Period4
Blockd
Protons27 p+
Neutrons32 n0
Electrons27 e-
Kobalt electrolytic and 1cm3 cube.jpg Animated Bohr Model Enhanced Bohr Model Bohr Model Orbital Diagram

Properties

Atomic Radius
135 pm
Atomic Volume
Covalent Radius
111.00000000000001 pm
Metallic Radius
116 pm
Ionic Radius
58 pm
Crystal Radius
72 pm
Van der Waals radius
200 pm
Density
8.86 g/cm³
Boiling Point
3,143 K
Melting Point
1,768 K
Electrons per shell2, 8, 15, 2
Electronegativity
1.88
Electrophilicity
1.2638504937544 eV/particle
Proton Affinity
742.7 kJ/mol
Electron Affinity
0.66225646 eV/particle
Ionization Potential
7.88101 eV/particle
Heat of Vaporization
389.1 kJ/mol
Heat of Fusion
15.48 kJ/mol
Heat of Formation
426.7 kJ/mol
Molar Heat Capacity
24.81 J/(mol K)
Specific Heat Capacity
0.421 J/(g⋅K)
Thermal Conductivity
Gas Basicity
719.8 kJ/mol
Dipole Polarizability
55 a₀
C6 Dispersion Coefficient
408 a₀
Oxidation States-1, 1, 2, 3, 4, 5
Color
Gray
Crystal StructureSimple Hexagonal (HEX)
Lattice Constant
2.51 Å
Bulk Modulus
Electrical Resistivity
Electron Configuration[Ar] 3d7 4s2
Magnetic Ordering
Magnetic Susceptibility
PhaseSolid
Poisson Ratio
Shear Modulus
Young's Modulus
Allotropes
Alternate Names
Adiabatic Index
Appearance
Electric Conductivity
Critical Pressure
Critical Temperature
Curie Point
Electrical
Hardness
Magnetic Susceptibility
Magnetic
Neel Point
Neutron Cross Section
Neutron Mass Absorption
Gas Phase
Quantum Numbers
Refractive Index
Space Group
Speed of Sound
Superconducting Point
Thermal Expansion
Valence Electrons
Classification
CategoryTransition metals, Transition metals
CAS GroupVIIIA
IUPAC GroupVIII
Glawe Number70
Mendeleev Number63
Pettifor Number64
Geochemical Classfirst series transition metal
Goldschmidt Classsiderophile
Radioactivity
RadioactiveNo
Decay Mode
Half-Life
Lifetime
Abundance
Abundance in Earth's crust
Abundance in Oceans
0.00002 mg/L
Abundance in Human Body
Abundance in Meteor
Abundance in Sun
Abundance in Universe0.0003%

Isotopes of Cobalt

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

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. From the German word Kobald, goblin or evil spirit; also from the Greek cobalos, mine

DiscoverersGeorge Brandt
Discovery LocationSweden
Discovery Year1739
Name OriginGerman: kobold (goblin).
Cobalt and its compounds are considered to be slightly toxic
Supplemental colbalt is essential in sheep's diets to improve the wools quality

Uses

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. Used in many hard alloys; for magnets, ceramics and special glasses. Remains hard up to 982°C. Radioactive cobalt-60 is used in cancer therapy.

Sources

Occurs in compounds with arsenic, oxygen and sulfur as in cobaltine (CoAsS) and linneite (Co3S4). Pure cobalt is obtained as a byproduct of refining nickel, copper and iron.