Skip to main content

Chromium

Source of the photo
sun-stone.en.alibaba.com/productshowimg
Author of the description
Gruiz Katalin, Fenyvesi Éva

Atomic number

24

Atomic mass

51.996 g.mol -1

Electronegativity

1.6

Density

7.19 g.cm-3 at 20°C

Melting point

1907 °C

Boiling point

2672 °C

Vanderwaals radius

0.127 nm

Ionic radius

0.061 nm (+3) ; 0.044 nm (+6)

Isotopes

6

Electronic shell

[ Ar ] 3d5 4s1

Energy of first ionisation

651.1 kJ.mol -1

Energy of second ionisation

1590.1 kJ.mol -1

Energy of third ionisation

2987 kJ.mol -1

Standard potential

- 0.71 V (Cr3+ / Cr )

Discovered by

Vaughlin in 1797

 

Chromium is a lustrous, brittle, hard metal. Its colour is silver-gray and it can be highly polished. It does not tarnish in air, when heated it borns and forms the green chromic oxide. Chromium is unstable in oxygen, it immediately produces a thin oxide layer that is impermeable to oxygen and protects the metal below.

Applications

Chromium main uses are in alloys such as stainless steel, in chrome plating and in metal ceramics. Chromium plating was once widely used to give steel a polished silvery mirror coating. Chromium is used in metallurgy to impart corrosion resistance and a shiny finish; as dyes and paints, its salts colour glass an emerald green and it is used to produce synthetic rubies; as a catalyst in dyeing and in the tanning of leather; to make molds for the firing of bricks. Chromium (IV) oxide (CrO2) is used to manufacture magnetic tape.

Source of description

http://www.lenntech.com/periodic/elements/cr.htm

Fémek és vegyületeik