About

Chromium is a hard, shiny, steel-gray metal known for its high polish and exceptional resistance to tarnish and corrosion. It is widely used for decorative and protective chrome plating on cars, fixtures, and tools. It's also the key alloying element that makes stainless steel 'stainless', typically at a concentration of 10% or more. Its compounds are also used as colorful pigments.

Atomic Properties

Atomic Number24

Atomic Weight51.996 u

Neutrons (common)28

Electron Configuration[Ar] 3d⁵ 4s¹

Full Configuration1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁵ 4s¹

Electrons per Shell2, 8, 13, 1

Electronegativity1.66

Electron Affinity64.3 kJ/mol

Oxidation States+6, +3, +2

Covalent Radius127 pm

Ionic Radius52 pm

Periodic Table Position

Group6

Period4

BlockD

Chemical SeriesTransition metals

Physical Properties

State at STPsolid

Appearancesteely-gray, lustrous, hard metal

Crystal Structurebcc

Magnetic Orderingantiferromagnetic

Speed of Sound5,940 m/s

Poisson Ratio0.21

Thermal Properties

Melting Point2,180 K

Boiling Point2,944 K

Triple Point2,180 K

Thermal Expansion4.9 1/K

Thermal Conductivity93.9 W/(m·K)

Specific Heat0.449 J/(g·K)

Molar Heat23.35 J/(mol·K)

Heat of Fusion21 kJ/mol

Heat of Vaporization347 kJ/mol

Abundance

In Earth's Crust102 ppm

In Ocean0.001 ppm

In Solar System10 ppm

In Human Body0.03 ppm

In Universe15 ppm

Discovery

Discovered byLouis Nicolas Vauquelin

Discovery Year1,797

Occurrenceprimordial

CAS Number7440-47-3

Electron Configuration

Energy

↿⇂

↿

Isotopes of Chromium

Symbol ▲	Mass (u) ▲	Abundance ▲	Half-life ▲	Decay Mode ▲
⁵⁰Cr	49.946040	4.345%	Stable	Stable
⁵¹Cr	50.944767	—	27.7015 d	Electron Capture
⁵²Cr	51.940510	83.789%	Stable	Stable
⁵³Cr	52.940650	9.501%	Stable	Stable
⁵⁴Cr	53.938880	2.365%	Stable	Stable

Interactive Visualization

Explore the 3D Bohr model of Chromium in our interactive viewer.

View 3D Model of Chromium