WebElements

Periodic Table

cobalt

Atomic number: 27
Atomic weight: 58.933200
Symbol: Co
Group number: 9
Electronic configuration: [Ar].3d7.4s2

Description

Cobalt is a brittle, hard, transition metal with magnetic properties similar to those of iron. Cobalt is present in meteorites. Ore deposits are found in Zaire, Morocco and Canada. Cobalt-60 (60Co) is an artificially produced isotope used as a source of g rays (high energy radiation). Cobalt salts colour glass a beautiful deep blue colour.

General information

Discoveror: Georg Brandt
Date discovered: 1735
Discovered at: Sweden
Meaning of name: From the German word "kobald" meaning "goblin" or evil spirit

Physical data

Standard state: solid at 298 K
Colour: lustrous, metallic, greyish tinge
Density of solid at ambient temperature/kg m-3: 8900
Molar volume/cm3: 6.67

Radii /pm

Atomic: 152
Covalent (single bond):
Pauling radius for the ion [Co]-: no data

Valence shell orbital radius maxima (Rmax)
orbital s p d f
radius131.9no data35.8no data

Electronegativities

Both values are quoted on the Pauling scale.

Pauling: 1.88
Allred Rochow: 1.7

Crystal Structure

structure: hcp (hexagonal close-packed)

The following CrystalMaker image represents the solid state structure. For most elements, the most stable allotrope is illustrated. Try WebElements version 2 for interactive virtual reality and CHIME images.

ball-and-stick.gif

Temperatures (/K)

melting point: 1768
boiling point: 3200

Enthalpies /kJ mol-1

fusion: 16.2
vaporization: 375

single bond enthalpies:
Co-F Co-Cl Co-Br Co-I Co-Co
no data no data no data no data 167

Ionization enthalpies /kJ mol-1

Number Enthalpy
1st758.0
2nd1646
3rd3232
4th4950
5th7670
6th9840
7th12400
8th15100

Isotopes

This section gives some data for naturally occurring isotopes.
Nominal mass Accurate mass % natural abundance
59Co58.9331976 (16)100

Further Information

Copyright 1997 Mark Winter
Department of Chemistry at the University of Sheffield, Sheffield S3 7HF, England.

The current version of this document is at http://www.shef.ac.uk/~chem/web-elements-I/Co.html