Cobalt

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Cobalt
27Co
-

Co

Rh
ironcobaltnickel
Appearance
haird lustrous gray metal
General properties
Name, seembol, nummer cobalt, Co, 27
Pronunciation /ˈkbɒlt/ KOH-bolt[1]
Element category transeetion metal
Group, period, block 9, 4, d
Staundart atomic wicht 58.933194(4)
Electron confeeguration [Ar] 4s2 3d7
2, 8, 15, 2
Electron shells of cobalt (2, 8, 15, 2)
History
Discovery Georg Brandt (1732)
Physical properties
Color metallic gray
Phase solid
Density (near r.t.) 8.90 g·cm−3
Liquid density at m.p. 7.75 g·cm−3
Meltin pynt 1768 K, 1495 °C, 2723 °F
Boilin pynt 3200 K, 2927 °C, 5301 °F
Heat o fusion 16.06 kJ·mol−1
Heat o vaporization 377 kJ·mol−1
Molar heat capacity 24.81 J·mol−1·K−1
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 1790 1960 2165 2423 2755 3198
Atomic properties
Oxidation states 5, 4, 3, 2, 1, -1[2]
(amphoteric oxide)
Electronegativity 1.88 (Pauling scale)
Ionization energies
(more)
1st: 760.4 kJ·mol−1
2nt: 1648 kJ·mol−1
3rd: 3232 kJ·mol−1
Atomic radius 125 pm
Covalent radius 126±3 (law spin), 150±7 (heich spin) pm
Miscellanea
Crystal structure hexagonal close-packed
Cobalt has a hexagonal close packed crystal structure
Magnetic orderin ferromagnetic
Electrical resistivity (20 °C) 62.4 nΩ·m
Thermal conductivity 100 W·m−1·K−1
Thermal expansion (25 °C) 13.0 µm·m−1·K−1
Speed of sound (thin rod) (20 °C) 4720 m·s−1
Young's modulus 209 GPa
Shear modulus 75 GPa
Bulk modulus 180 GPa
Poisson ratio 0.31
Mohs hairdness 5.0
Vickers hairdness 1043 MPa
Brinell hairdness 700 MPa
CAS registry nummer 7440-48-4
Most stable isotopes
Main article: Isotopes o cobalt
iso NA hauf-life DM DE (MeV) DP
56Co syn 77.27 d ε 4.566 56Fe
57Co syn 271.79 d ε 0.836 57Fe
58Co syn 70.86 d ε 2.307 58Fe
59Co 100% 59Co is stable wi 32 neutrons
60Co syn 5.2714 y β, γ 2.824 60Ni
· r

Cobalt is a chemical element wi seembol Co an atomic nummer 27. Lik nickel, cobalt in the Yird's crust is foond anly in chemically combined furm, save for smaa deposits foond in alloys o naitural meteoric iron. The free element, produced bi reductive smeltin, is a haird, lustrous, siller-gray metal.

References[eedit | eedit soorce]

  1. Oxford English Dictionary, 2nd Edition 1989.
  2. Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth–Heinemann. pp. 1117–1119. ISBN 0080379419.