chromium

• Description
• General information
• Physical data
• Radii
• Electronegativities
• Solid state structure
• Temperatures
• Enthalpies
• Ionization Enthalpies
• Isotopes
• Further information

Description

Chromium is steel-gray, lustrous, hard, metallic, and takes a high polish. Its compounds are toxic. It is found as chromite ore. Siberian red lead is a chromium ore prized as a red pigment for oil paints.

General information

Discoveror: Louis-Nicholas Vauquelin
Date discovered: 1797
Discovered at: France
Meaning of name: From the Greek word "chroma" meaning "colour"

Physical data

Standard state: solid at 298 K
Colour: silvery metallic
Density of solid at ambient temperature/kg m^-3: 7140
Molar volume/cm³: 7.23

Radii /pm

Atomic: 166
Covalent (single bond):
Pauling radius for the ion [Cr]^-: no data

Valence shell orbital radius maxima (R_max)

orbital	s	p	d	f
radius	162.6	no data	45.5	no data

Electronegativities

Both values are quoted on the Pauling scale.

Pauling: 1.66
Allred Rochow: 1.56

Crystal Structure

structure: bcc (body-centred cubic)

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.

Temperatures (/K)

melting point: 2180
boiling point: 2944

Enthalpies /kJ mol^-1

fusion: 20.5
vaporization: 350

single bond enthalpies:

Cr-F	Cr-Cl	Cr-Br	Cr-I	Cr-Cr
no data	no data	no data	no data	155

Ionization enthalpies /kJ mol^-1

Number	Enthalpy
1st	652.8
2nd	1496
3rd	2987
4th	4740
5th	6690
6th	8738
7th	15550
8th	17820

Isotopes

This section gives some data for naturally occurring isotopes.

Nominal mass	Accurate mass	% natural abundance
50Cr	49.9460464 (17)	4.345 (9)
52Cr	51.9405098 (17)	83.789 (12)
53Cr	52.9406513 (17)	9.501 (11)
54Cr	53.9388825 (17)	2.365 (5)

Further Information

• Additional information about WebElements 1.2.2
• This is a licensed copy (here is the full list) of WebElements 1.2.2 and contains a subset of the material contained within the main version of WebElements (version 2)
• For further information please try WebElements version 2
• Sheffield Chemdex: perhaps the largest internet chemistry directory
• Sheffield Chemputer: interactive chemistry calculators on the WWW