From Wikipedia, the free encyclopedia

iron ← cobalt → nickel - ↑ Co ↓ Rh 27Co Periodic table

hard lustrous gray metal

cobalt, Co, 27

transition metal

9, 4, d

58.933195(5) g·mol−1

[Ar] 4s2 3d7

2, 8, 15, 2 (Image)

metallic gray

8.90 g·cm−3

7.75 g·cm−3

1768 K, 1495 °C, 2723 °F

3200 K, 2927 °C, 5301 °F

16.06 kJ·mol−1

377 kJ·mol−1

(25 °C) 24.81 J·mol−1·K−1

P/Pa 1 10 100 1 k 10 k 100 k at T/K 1790 1960 2165 2423 2755 3198

5, 4 , 3, 2, 1, -1[1] (amphoteric oxide)

1.88 (Pauling scale)

1st: 760.4 kJ·mol−1

2nd: 1648 kJ·mol−1

3rd: 3232 kJ·mol−1

125 pm

126±3 (low spin), 150±7 (high spin) pm

hexagonal

ferromagnetic

(20 °C) 62.4 nΩ·m

(300 K) 100 W·m−1·K−1

(25 °C) 13.0 µm·m−1·K−1

(20 °C) 4720 m/s

209 GPa

75 GPa

180 GPa

0.31

5.0

1043 MPa

700 MPa

7440-48-4

Main article: Isotopes of cobalt

isoNAhalf-lifeDMDE (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 with 32 neutrons 60Co syn 5.2714 years β−,γ,γ 2.824 60Ni

This box: view • talk • edit

Cobalt (pronounced /ˈkoʊbɒlt/ KOH-bolt)[2] is a hard, lustrous, gray metal, a chemical element with symbol Co and atomic number 27. Cobalt-based colors and pigments have been used since ancient times for jewelry and paints, and miners have long used the name kobold ore for some minerals.

Cobalt occurs in various metallic-lustered ores, for example cobaltite (CoAsS), but is mainly produced as a by-product of copper and nickel mining. The copper belt in the Democratic Republic of the Congo and Zambia yields most of the cobalt mined worldwide.

Cobalt is used in the preparation of magnetic, wear-resistant, and high-strength alloys. Smalte (cobalt silicate glass) and cobalt blue (cobalt(II) aluminate, CoAl2O4) gives a distinctive deep blue color to glass, ceramics, inks, paints, and varnishes. Cobalt-60 is a commercially important radioisotope, used as a tracer and in the production of gamma rays for industrial use.

Cobalt is an essential trace element for all multicellular organisms as the active center of coenzymes called cobalamins. These include vitamin B-12 which is essential for mammals. Cobalt is also an active nutrient for bacteria, algae, and fungi, and may be a necessary nutrient for all life.