Chromium is a steely-grey, lustrous, hard, brittle metal which takes a high polish, resists tarnishing, and has a high melting point. Chromium oxide was used by the Chinese in the Qin dynasty over 2,000 years ago to coat weapons found with the Terracotta Army.

1797 by Louis-Nicholas Vauquelin, France.

DISCOVERY

Ancient Greek, χρῶμα (khrôma, 'colour') + -ium.

ETYMOLOGY

Chromium

Element

Cr

Symbol

24

24 Atomic Number

Atomic Number

Transition Metal

Classification

7440-47-3

CAS Number

Silver

Elemental Colour

-

Refractive Index

0.210

0.210 Poisson Ratio

Poisson Ratio

7.282 cm³

Molar Volume

1.12G Pa, 11.053'5k Atm

11.053'5k Atm

Brinell Hardness

8.50

8.50 Mohs Hardness

Mohs Hardness

1.06G Pa, 10.461'4k Atm

10.461'4k Atm

Vickers Hardness

5,940 m/s, Mach 17.317'8

5,940 m/s

Speed of Sound

160.00G Pa, 1.579'1M Atm

1.579'1M Atm

Bulk Modulus

115.00G Pa, 1.135'0M Atm

1.135'0M Atm

Shear Modulus

279.00G Pa, 2.753'5M Atm

2.753'5M Atm

Young Modulus

Allotropes

2,180.15 K, 1,907.00 °C

1,907.00 °C

Melting Point

2,944.15 K, 2,671.00 °C

2,671.00 °C

Boiling Point

673.15 K, 400.00 °C

400.00 °C

Automatic Ignition

-

Flashpoint

-

Critical Temperature

-

Critical Pressure

94.000'000 W/(m K)

Thermal Conductivity

0.000'004'9 K^-1

Thermal Expansion

448.00 J/(kg K)

Specific Heat

20.500 kJ/mol

Heat Fusion

339.000 kJ/mol

Heat Vaporisation

-

Heat Combustion

-

Curie Point

393.00 K, 119.85 °C

119.85 °C

Neel Point

-

Adiabatic Index

Solid

Phase

Conductor

Electrical Type

7.90M S/m

Conductivity

130.00n Ω.m

Resistivity

-

Superconducting Point

Antiferromagnetic

Magnetic Type

0.000'000'044'5

Mass Susceptibility

0.000'000'002'314'00

Molar Susceptibility

0.000'317'700'00

Volume Susceptibility

Material Composition

0.001'5 %

Universe

0.3 %

Meteorites

0.002 %

Sun

0.014 %

Earth Crust

0.000'000'06 %

Oceans

0.000'003 %

Humans

51.996'133'0

Atomic Weight

166 pm

Atomic Radius

122 pm

Covalent Radius Single Bond

111 pm

Covalent Radius Double Bond

103 pm

Covalent Radius Triple Bond

189 pm

Van der Waals Radius

[Ar]4s¹3d⁵

Electron Configuration

Cubic, Body-centred

Crystal Structure

7.140'00 g/cm³

Density as Solid

6.300'00 g/cm³

Density as Liquid

-

Density as Gas

lm_3m

Space Group Name

229

229 Space Group Number

Space Group Number

π/2, π/2 & π/2

Lattice Angles

291, 291 & 291 pm

Lattice Constants

6

6 Valence

Valence

1.66

1.66 Electronegativity

Electronegativity

65.21 kJ/mol

Electron Affinity

Ionisation Energy

Stable

Half Life

Stable

Lifetime

3d⁵ = 3, 2, +2, +1/2

Quantum Numbers

3.490'00 b σ_s

Neutron Cross Section

3.050'00 b σ_a

Neutron Mass Absorption

Stable Isotopes

Unstable Isotopes

Isotopes Overview

Isotope	Stability	Symbol	Type	Protons		Neutrons		Spin	Parity	Mass		Abundance		Mass Measure	Mass Excess		Binding Energy		Dipole Moment		Quadrupole Moment		Halflife in Years		Halflife in Seconds		A01 Decay Probability		A01 Decay Mode	A01 Decay Energy		A01 Decay Daughter	A01 Decay Link	A02 Decay Probability		A02 Decay Mode	A02 Decay Energy		A02 Decay Daughter	A02 Decay Link	A03 Decay Probability		A03 Decay Mode	A03 Decay Energy		A03 Decay Daughter	A03 Decay Link	A04 Decay Probability		A04 Decay Mode	A04 Decay Energy		A04 Decay Daughter	A04 Decay Link	Y01 Decay Product Yield		Y01 Decay Product Nuclide	Y02 Decay Product Yield		Y02 Decay Product Nuclide	Y03 Decay Product Yield		Y03 Decay Product Nuclide	Y04 Decay Product Yield		Y04 Decay Product Nuclide
Isotope_024_cr_42_u	Unstable	⁴²Cr	Boson	24	p	18	n	0	1	42.006'430'000'0	u	~ 0	%	~ 0	5.990'000'000'0	MeV	7.482'000'000'0	MeV	-		-		4.44E-10	year	14.000	milli-seconds ( x⁻³ )	100.000'000	%	β+	13,137.000	keV	⁴²V	⁴²Cr > [ 100 % , β+ , 13,137.0 keV ] > ⁴²V	?	%	2p	262.000	keV	⁴⁰Ti	⁴²Cr > [ ? % , 2p , 262.0 keV ] > ⁴⁰Ti	?	%	β+p	?	keV	⁴¹Ti	⁴²Cr > [ ? % , β+p , ? keV ] > ⁴¹Ti								?	%	³⁹K	?	%	⁴⁰Ar
Isotope_024_cr_43_u	Unstable	⁴³Cr	Fermion	24	p	19	n	3/2	1	42.997'710'000'0	u	~ 0	%	~ 0	-2.133'000'000'0	MeV	7.684'000'000'0	MeV	-		-		6.84E-10	year	21.600	milli-seconds ( x⁻³ )	71.000'000	%	β+	14,869.000	keV	⁴³V	⁴³Cr > [ 71 % , β+ , 14,869.0 keV ] > ⁴³V	23.000'000	%	β+p	?	keV	⁴²Ti	⁴³Cr > [ 23 % , β+p , ? keV ] > ⁴²Ti	6.000'000	%	β+2p	?	keV	⁴¹Sc	⁴³Cr > [ 6 % , β+2p , ? keV ] > ⁴¹Sc	?	%	β+α	?	keV	³⁹Sc	⁴³Cr > [ ? % , β+α , ? keV ] > ³⁹Sc	23.000'000	%	⁴²Ca	6.000'000	%	⁴¹K	?	%	⁴³Ca	?	%	³⁸Ar
Isotope_024_cr_44_u	Unstable	⁴⁴Cr	Boson	24	p	20	n	0	1	43.985'549'000'0	u	~ 0	%	~ 0	-13.461'000'000'0	MeV	7.951'000'000'0	MeV	-		-		1.71E-9	year	54.000	milli-seconds ( x⁻³ )	93.000'000	%	β+	9,633.000	keV	⁴⁴V	⁴⁴Cr > [ 93 % , β+ , 9,633.0 keV ] > ⁴⁴V	7.000'000	%	β+p	?	keV	⁴³Ti	⁴⁴Cr > [ 7 % , β+p , ? keV ] > ⁴³Ti															93.000'000	%	⁴⁴Ca	7.000'000	%	⁴³Ca	?	%	⁴⁰Ar
Isotope_024_cr_45_u	Unstable	⁴⁵Cr	Fermion	24	p	21	n	7/2	1	44.979'640'000'0	u	~ 0	%	~ 0	-18.965'218'000'0	MeV	8.075'515'000'0	MeV	-		-		1.58E-9	year	50.000	milli-seconds ( x⁻³ )	73.000'000	%	β+	11,892.000	keV	⁴⁵V	⁴⁵Cr > [ 73 % , β+ , 11,892.0 keV ] > ⁴⁵V	27.000'000	%	β+p	?	keV	⁴⁴Ti	⁴⁵Cr > [ 27 % , β+p , ? keV ] > ⁴⁴Ti															73.000'000	%	⁴⁵Sc	27.000'000	%	⁴⁴Ca
Isotope_024_cr_46_u	Unstable	⁴⁶Cr	Boson	24	p	22	n	0	1	45.968'358'635'0	u	~ 0	%	~ 0	-29.473'742'000'0	MeV	8.303'870'000'0	MeV	-		-		8.24E-9	year	260.000	milli-seconds ( x⁻³ )	100.000'000	%	β+	6,577.000	keV	⁴⁶V	⁴⁶Cr > [ 100 % , β+ , 6,577.0 keV ] > ⁴⁶V																						100.000'000	%	⁴⁶Ti
Isotope_024_cr_47_u	Unstable	⁴⁷Cr	Fermion	24	p	23	n	3/2	-1	46.962'900'046'0	u	~ 0	%	~ 0	-34.558'385'000'0	MeV	8.407'106'000'0	MeV	-		-		1.58E-8	year	500.000	milli-seconds ( x⁻³ )	100.000'000	%	β+	6,421.500	keV	⁴⁷V	⁴⁷Cr > [ 100 % , β+ , 6,421.5 keV ] > ⁴⁷V																						100.000'000	%	⁴⁷Ti
Isotope_024_cr_48_u	Unstable	⁴⁸Cr	Boson	24	p	24	n	0	1	47.954'031'716'0	u	~ 0	%	~ 0	-42.819'180'000'0	MeV	8.572'210'000'0	MeV	-		-		5.75E-2	year	1.814	mega-seconds ( x⁶ )	100.000'000	%	β+	634.010	keV	⁴⁸V	⁴⁸Cr > [ 100 % , β+ , 634.01 keV ] > ⁴⁸V																						100.000'000	%	⁴⁸Ti
Isotope_024_cr_49_u	Unstable	⁴⁹Cr	Fermion	24	p	25	n	5/2	-1	48.951'335'721'0	u	~ 0	%	~ 0	-45.330'484'000'0	MeV	8.613'239'000'0	MeV	0.476'000'000'0	nm	-		8.05E-5	year	2.540	kilo-seconds ( x³ )	100.000'000	%	β+	1,604.000	keV	⁴⁹V	⁴⁹Cr > [ 100 % , β+ , 1,604.0 keV ] > ⁴⁹V																						100.000'000	%	⁴⁹Ti
Isotope_024_cr_50_s	Stable	⁵⁰Cr	Boson	24	p	26	n	0	1	49.946'044'205'0	u	4.345'000	%	2.170'155'620'7	-50.259'499'000'0	MeV	8.700'981'000'0	MeV	-		-		-				?	%	2β+	-877.230	keV	⁵⁰V	⁵⁰Cr > [ ? % , 2β+ , -877.23 keV ] > ⁵⁰V																						?	%	⁵⁰Ti
Isotope_024_cr_51_u	Unstable	⁵¹Cr	Fermion	24	p	27	n	7/2	-1	50.944'767'431'0	u	~ 0	%	~ 0	-51.448'807'000'0	MeV	8.711'954'000'0	MeV	-0.934'000'000'0	nm	-		7.58E-2	year	2.393	mega-seconds ( x⁶ )	100.000'000	%	ϵ	752.576	keV	⁵¹V	⁵¹Cr > [ 100 % , ϵ , 752.576 keV ] > ⁵¹V																						100.000'000	%	⁵¹Ti
Isotope_024_cr_52_s	Stable	⁵²Cr	Boson	24	p	28	n	0	1	51.940'507'472'0	u	83.789'000	%	43.520'431'805'7	-55.416'933'000'0	MeV	8.775'944'000'0	MeV	-		-		-
Isotope_024_cr_53_s	Stable	⁵³Cr	Fermion	24	p	29	n	3/2	-1	52.940'649'386'0	u	9.501'000	%	5.029'891'098'2	-55.284'741'000'0	MeV	8.760'155'000'0	MeV	-0.474'540'000'0	nm	-0.150'000'000'0	b	-
Isotope_024_cr_54_s	Stable	⁵⁴Cr	Boson	24	p	30	n	0	1	53.938'880'395'0	u	2.365'000	%	1.275'654'521'3	-56.932'545'000'0	MeV	8.777'914'000'0	MeV	-		-		-
Isotope_024_cr_55_u	Unstable	⁵⁵Cr	Fermion	24	p	31	n	3/2	-1	54.940'839'672'0	u	~ 0	%	~ 0	-55.107'491'000'0	MeV	8.731'884'000'0	MeV	-		-		6.46E-6	year	204.000	seconds ( x⁰ )	100.000'000	%	β-	2,603.089	keV	⁵⁵Mn	⁵⁵Cr > [ 100 % , β- , 2,603.089 keV ] > ⁵⁵Mn																						100.000'000	%	⁵⁵Mn
Isotope_024_cr_56_u	Unstable	⁵⁶Cr	Boson	24	p	32	n	0	1	55.940'653'139'0	u	~ 0	%	~ 0	-55.281'245'000'0	MeV	8.723'191'000'0	MeV	-		-		1.13E-5	year	355.980	seconds ( x⁰ )	100.000'000	%	β-	1,628.460	keV	⁵⁶Mn	⁵⁶Cr > [ 100 % , β- , 1,628.46 keV ] > ⁵⁶Mn																						100.000'000	%	⁵⁶Fe
Isotope_024_cr_57_u	Unstable	⁵⁷Cr	Fermion	24	p	33	n	3/2	-1	56.943'613'013'0	u	~ 0	%	~ 0	-52.524'140'000'0	MeV	8.663'384'000'0	MeV	-		-		6.69E-7	year	21.100	seconds ( x⁰ )	100.000'000	%	β-	4,962.660	keV	⁵⁷Mn	⁵⁷Cr > [ 100 % , β- , 4,962.66 keV ] > ⁵⁷Mn																						100.000'000	%	⁵⁷Fe
Isotope_024_cr_58_u	Unstable	⁵⁸Cr	Boson	24	p	34	n	0	1	57.944'353'129'0	u	~ 0	%	~ 0	-51.834'726'000'0	MeV	8.641'290'000'0	MeV	-		-		2.22E-7	year	7.000	seconds ( x⁰ )	100.000'000	%	β-	4,072.000	keV	⁵⁸Mn	⁵⁸Cr > [ 100 % , β- , 4,072.0 keV ] > ⁵⁸Mn																						100.000'000	%	⁵⁸Fe
Isotope_024_cr_59_u	Unstable	⁵⁹Cr	Fermion	24	p	35	n	5/2	-1	58.948'586'367'0	u	~ 0	%	~ 0	-47.891'490'000'0	MeV	8.564'795'000'0	MeV	-		-		1.46E-8	year	460.000	milli-seconds ( x⁻³ )	100.000'000	%	β-	7,588.000	keV	⁵⁹Mn	⁵⁹Cr > [ 100 % , β- , 7,588.0 keV ] > ⁵⁹Mn																						100.000'000	%	⁵⁹Co
Isotope_024_cr_60_u	Unstable	⁶⁰Cr	Boson	24	p	36	n	0	1	59.950'076'033'0	u	~ 0	%	~ 0	-46.503'876'000'0	MeV	8.533'443'000'0	MeV	-		-		1.65E-8	year	520.000	milli-seconds ( x⁻³ )	100.000'000	%	β-	6,674.000	keV	⁶⁰Mn	⁶⁰Cr > [ 100 % , β- , 6,674.0 keV ] > ⁶⁰Mn																						100.000'000	%	⁶⁰Ni
Isotope_024_cr_61_u	Unstable	⁶¹Cr	Fermion	24	p	37	n	5/2	-1	60.954'717'204'0	u	~ 0	%	~ 0	-42.180'653'000'0	MeV	8.454'995'000'0	MeV	-		-		8.27E-9	year	261.000	milli-seconds ( x⁻³ )	100.000'000	%	β-	9,375.000	keV	⁶¹Mn	⁶¹Cr > [ 100 % , β- , 9,375.0 keV ] > ⁶¹Mn	?	%	β-n	2,926.000	keV	⁶⁰Mn	⁶¹Cr > [ ? % , β-n , 2,926.0 keV ] > ⁶⁰Mn															100.000'000	%	⁶¹Ni	?	%	⁶⁰Ni
Isotope_024_cr_62_u	Unstable	⁶²Cr	Boson	24	p	38	n	0	1	61.956'613'190'0	u	~ 0	%	~ 0	-40.414'553'000'0	MeV	8.420'321'000'0	MeV	-		-		6.31E-9	year	199.000	milli-seconds ( x⁻³ )	100.000'000	%	β-	7,624.000	keV	⁶²Mn	⁶²Cr > [ 100 % , β- , 7,624.0 keV ] > ⁶²Mn	?	%	β-n	3,070.000	keV	⁶¹Mn	⁶²Cr > [ ? % , β-n , 3,070.0 keV ] > ⁶¹Mn															100.000'000	%	⁶²Ni	?	%	⁶¹Ni	?	%	⁶⁰Ni
Isotope_024_cr_63_u	Unstable	⁶³Cr	Fermion	24	p	39	n	1/2	-1	62.961'860'000'0	u	~ 0	%	~ 0	-35.527'000'000'0	MeV	8.337'000'000'0	MeV	-		-		4.09E-9	year	129.000	milli-seconds ( x⁻³ )	100.000'000	%	β-	10,824.000	keV	⁶³Mn	⁶³Cr > [ 100 % , β- , 10,824.0 keV ] > ⁶³Mn	?	%	β-n	4,440.000	keV	⁶²Mn	⁶³Cr > [ ? % , β-n , 4,440.0 keV ] > ⁶²Mn															100.000'000	%	⁶³Ni	?	%	⁶²Ni	?	%	⁶¹Ni
Isotope_024_cr_64_u	Unstable	⁶⁴Cr	Boson	24	p	40	n	0	1	63.964'410'000'0	u	~ 0	%	~ 0	-33.152'000'000'0	MeV	8.296'000'000'0	MeV	-		-		1.36E-9	year	43.000	milli-seconds ( x⁻³ )	100.000'000	%	β-	9,465.000	keV	⁶⁴Mn	⁶⁴Cr > [ 100 % , β- , 9,465.0 keV ] > ⁶⁴Mn																						100.000'000	%	⁶⁴Ni	?	%	⁶³Cu
Isotope_024_cr_65_u	Unstable	⁶⁵Cr	Fermion	24	p	41	n	1/2	-1	64.970'160'000'0	u	~ 0	%	~ 0	-27.796'000'000'0	MeV	8.210'000'000'0	MeV	-		-		8.56E-10	year	27.000	milli-seconds ( x⁻³ )	100.000'000	%	β-	12,877.000	keV	⁶⁵Mn	⁶⁵Cr > [ 100 % , β- , 12,877.0 keV ] > ⁶⁵Mn	?	%	β-n	6,750.000	keV	⁶⁴Mn	⁶⁵Cr > [ ? % , β-n , 6,750.0 keV ] > ⁶⁴Mn															100.000'000	%	⁶⁵Ni	?	%	⁶⁴Ni	?	%	⁶³Cu
Isotope_024_cr_66_u	Unstable	⁶⁶Cr	Boson	24	p	42	n	0	1	65.973'380'000'0	u	~ 0	%	~ 0	-24.796'000'000'0	MeV	8.163'000'000'0	MeV	-		-		3.17E-10	year	10.000	milli-seconds ( x⁻³ )	100.000'000	%	β-	11,457.000	keV	⁶⁶Mn	⁶⁶Cr > [ 100 % , β- , 11,457.0 keV ] > ⁶⁶Mn																						100.000'000	%	⁶⁶Ni	?	%	⁶⁵Cu
Isotope_024_cr_67_u	Unstable	⁶⁷Cr	Fermion	24	p	43	n	1/2	-1	66.979'550'000'0	u	~ 0	%	~ 0	-19.049'000'000'0	MeV	8.075'000'000'0	MeV	-		-		3.17E-10	year	10.000	milli-seconds ( x⁻³ )	?	%	β-	14,354.000	keV	⁶⁷Mn	⁶⁷Cr > [ ? % , β- , 14,354.0 keV ] > ⁶⁷Mn																						?	%	⁶⁷Ni	?	%	⁶⁶Zn	?	%	⁶⁵Cu

24 – Chromium, Cr

24 – Chromium, Cr

24 – Chromium, Cr

24 – Chromium, Cr

24 – Chromium, Cr

Spectrograph

Elemental Tile

Chromium Ore

Spectrograph

Elemental Tile

Chromium Ore

Spectrograph

Elemental Tile

Chromium Ore

Spectrograph

Elemental Tile

Chromium Ore

Spectrograph

Elemental Tile

Chromium Ore