Chromium (Cr)

Chromium is the 24th element in the periodic table and has a symbol of Cr and atomic number of 24. It has an atomic weight of 51.9961 and a mass number of 52. Chromium has twenty-four protons and twenty-eight neutrons in its nucleus, and twenty-four electrons in four shells. It is located in group six, period four and block d of the periodic table. Hard silvery transition element. Used in decorative electroplating. Discovered in 1797 by Vauquelin.

Atomic Number	24
Atomic Weight	51.9961
Mass Number	52

Group	6
Period	4
Block	d

Protons	24 p⁺
Neutrons	28 n⁰
Electrons	24 e^-

Properties

Physical Properties
Atomic Radius	140 pm 233 pm
Molar Volume	7.23 cm³/mol
Covalent Radius	122 pm 111 pm 103 pm 140 pm 139 pm
Metallic Radius	119 pm 128 pm
Ionic Radius	73 pm 80 pm 61.5 pm 41 pm 55 pm 34.5 pm 49 pm 57 pm 26 pm 44 pm
Crystal Radius	87 pm 94 pm 75.5 pm 55 pm 69 pm 48.5 pm 63 pm 71 pm 40 pm 58 pm
Van der Waals Radius	205 pm 206 pm 225 pm 302.3 pm
Density	7.15 g/cm³ 6,300 kg/m³
Energy
Proton Affinity	791.3 kJ/mol
Electron Affinity	0.666 eV/particle
Ionization Energy	6.76651 eV/particle 16.486305 eV/particle 30.96 eV/particle 49.16 eV/particle 69.46 eV/particle 90.635 eV/particle 160.29 eV/particle 184.76 eV/particle 209.54 eV/particle 244.52 eV/particle 270.8 eV/particle 296.74 eV/particle 354.66 eV/particle 384.163 eV/particle 1,011.62 eV/particle 1,097.2 eV/particle 1,188 eV/particle 1,294.8 eV/particle 1,394.5 eV/particle 1,495.1 eV/particle 1,634 eV/particle 1,721.183 eV/particle 7,481.8625 eV/particle 7,894.799 eV/particle

Heat of Vaporization	342 kJ/mol
Heat of Fusion	21 kJ/mol
Heat of Formation	397.48 kJ/mol
Electrons
Electron Shells	2, 8, 13, 1

Valence Electrons	1
Electron Configuration	[Ar] 3d⁵ 4s¹

Oxidation States	-4, -2, -1, 0, 1, 2, 3, 4, 5, 6
Electronegativity	9.77 eV/particle 0.1313053 1.66
Electrophilicity	1.1319177597467263 eV/particle
Phases
Phase	Solid
Gas Phase
Boiling Point	2,944.15 K
Melting Point	2,180.15 K
Critical Pressure
Critical Temperature
Triple Point
Visual
Chromium is a Silver. Cr has a CPK of #808090, Jmol of #8a99c7, and MOLCAS GV of #8a99c7. The Appearance of Element 24 is silvery metallic.
Color	Silver #808090 #8a99c7 #8a99c7
Appearance	silvery metallic
Refractive Index
Thermodynamic Properties
Thermal Conductivity	93.9 W/(m K)
Thermal Expansion	0.0000049 1/K
Molar Heat Capacity	23.35 J/(mol K)
Specific Heat Capacity	0.449 J/(g⋅K)
Heat Capacity Ratio (Adiabatic Index)
Electrical Properties
Type	Conductor
Electrical Conductivity	7.9 MS/m
Electrical Resistivity	0.00000013 m Ω
Superconducting Point
Magnetism
Type	antiferromagnetic
Magnetic Susceptibility (Mass)	0.0000000445 m³/Kg
Magnetic Susceptibility (Molar)	0.000000002314 m³/mol
Magnetic Susceptibility (Volume)	0.0003177
Magnetic Ordering
Curie Point
Neel Point	393 K
Structure
The Crystal Structure of Chromium is BCC. The lattice constant of Cr is 2.88 Å. The lattice angles of Element 24 are π/2, π/2, π/2.
Crystal Structure	Body Centered Cubic (BCC)
Lattice Constant	2.88 Å
Lattice Angles	π/2, π/2, π/2
Mechanical Properties
Chromium has a Brinell of 1120 MPa, Mohs hardness of 8.5 MPa, and Vickers of 1060 MPa. The Bulk Modulus of Cr is 160 GPa. The Shear Modulus of Element 24 is 115 GPa. The Young Modulus of Chromium (Cr) is 279 GPa. The Poisson Ratio of Chromium is 0.21. The Speed of Sound of Cr is 5940 m/s.
Hardness	1,120 MPa 8.5 MPa 1,060 MPa
Bulk Modulus	160 GPa
Shear Modulus	115 GPa
Young Modulus	279 GPa
Poisson Ratio	0.21
Speed of Sound	5,940 m/s
Classification
The CAS Group of Chromium is VIA. The IUPAC Group of Cr is VIB. The Glawe Number of Element 24 is 55. The Mendeleev Number of Chromium (Cr) is 51. The Pettifor Number of Chromium is 57. The Geochemical Class of Cr is first series transition metal. The Goldschmidt Class of Element 24 is litophile.
Category	Transition metals, Transition metals
CAS Group	VIA
IUPAC Group	VIB
Glawe Number	55
Mendeleev Number	51
Pettifor Number	57
Geochemical Class	first series transition metal
Goldschmidt Class	litophile
Other
The Gas Basicity of Chromium is 768.4 kJ/mol. The Dipole Polarizability of Cr is 83 plus or minus 12 a₀. Element 24 has a C6 Dispersion Coefficient (CD) of 602 a₀, and C6 Dispersion Coefficient (GB) of 709 a₀. The Allotropes of Chromium (Cr) is . The Neutron Cross Section of Chromium is 3.1. The Neutron Mass Absorption of Cr is 0.0021. The Quantum Numbers of Element 24 is 7S3. The Space Group of Chromium (Cr) is 229 (Im_3m).
Gas Basicity	768.4 kJ/mol
Dipole Polarizability	83 ± 12 a₀
C6 Dispersion Coefficient	602 a₀ 709 a₀
Allotropes
Neutron Cross Section	3.1
Neutron Mass Absorption	0.0021
Quantum Numbers	7S3
Space Group	229 (Im_3m)

Isotopes of Chromium

Stable Isotopes	4
Unstable Isotopes	26
Radioactive Isotopes	25

⁴¹Cr

Abundance
Relative Atomic Mass	41.021911 ± 0.000429 Da
Mass Number	41
G-Factor
Half Life
Spin	3/2
Quadrupole Moment
Discovery Year
Parity	+

⁴¹Cr Decay Modes

Decay Mode	Intensity
p (proton emission)	%

⁴²Cr

Abundance	Radioactive ☢️
Relative Atomic Mass	42.007579 ± 0.000322 Da
Mass Number	42
G-Factor	0
Half Life	13.3 ± 1 ms
Spin	0
Quadrupole Moment	0
Discovery Year	1996
Parity	+

⁴²Cr Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%
β⁺ p (β⁺-delayed proton emission)	94.4%
2p (2-proton emission)	%

⁴³Cr

Abundance	Radioactive ☢️
Relative Atomic Mass	42.997885 ± 0.000215 Da
Mass Number	43
G-Factor
Half Life	21.1 ± 0.3 ms
Spin	3/2
Quadrupole Moment
Discovery Year	1992
Parity	+

⁴³Cr Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%
β⁺ p (β⁺-delayed proton emission)	79.3%
2p (2-proton emission)	11.6%
3p	0.13%
β⁺α (β⁺-delayed α emission)	%

⁴⁴Cr

Abundance	Radioactive ☢️
Relative Atomic Mass	43.985591 ± 0.000055 Da
Mass Number	44
G-Factor	0
Half Life	42.8 ± 0.6 ms
Spin	0
Quadrupole Moment	0
Discovery Year	1987
Parity	+

⁴⁴Cr Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%
β⁺ p (β⁺-delayed proton emission)	12%

⁴⁵Cr

Abundance	Radioactive ☢️
Relative Atomic Mass	44.97905 ± 0.000038 Da
Mass Number	45
G-Factor
Half Life	60.9 ± 0.4 ms
Spin	7/2
Quadrupole Moment
Discovery Year	1974
Parity	-

⁴⁵Cr Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%
β⁺ p (β⁺-delayed proton emission)	34.4%

⁴⁶Cr

Abundance	Radioactive ☢️
Relative Atomic Mass	45.968360969 ± 0.000012295 Da
Mass Number	46
G-Factor	0
Half Life	224.3 ± 1.3 ms
Spin	0
Quadrupole Moment	0
Discovery Year	1972
Parity	+

⁴⁶Cr Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

⁴⁷Cr

Abundance	Radioactive ☢️
Relative Atomic Mass	46.962894995 ± 0.000005578 Da
Mass Number	47
G-Factor
Half Life	461.6 ± 1.5 ms
Spin	3/2
Quadrupole Moment
Discovery Year	1972
Parity	-

⁴⁷Cr Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

⁴⁸Cr

Abundance	Radioactive ☢️
Relative Atomic Mass	47.954029431 ± 0.000007848 Da
Mass Number	48
G-Factor	0
Half Life	21.56 ± 0.03 h
Spin	0
Quadrupole Moment	0
Discovery Year	1952
Parity	+

⁴⁸Cr Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

⁴⁹Cr

Abundance	Radioactive ☢️
Relative Atomic Mass	48.95133372 ± 0.000002363 Da
Mass Number	49
G-Factor	0.1904 ± 0.0012
Half Life	42.3 ± 0.1 m
Spin	5/2
Quadrupole Moment
Discovery Year	1942
Parity	-

⁴⁹Cr Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

⁵⁰Cr

Abundance	4.345 ± 0.013
Relative Atomic Mass	49.946042209 ± 0.0000001 Da
Mass Number	50
G-Factor	0
Half Life
Spin	0
Quadrupole Moment	0
Discovery Year	1930
Parity	+

⁵⁰Cr Decay Modes

Decay Mode	Intensity
2β⁺ (double β⁺ decay)	%

⁵¹Cr

Abundance	Radioactive ☢️
Relative Atomic Mass	50.944765388 ± 0.000000178 Da
Mass Number	51
G-Factor	0.26685714285714 ± 0.0014285714285714
Half Life	27.7015 ± 0.0011 d
Spin	7/2
Quadrupole Moment
Discovery Year	1940
Parity	-

⁵¹Cr Decay Modes

Decay Mode	Intensity
ϵ (electron capture)	100%

⁵²Cr

Abundance	83.789 ± 0.018
Relative Atomic Mass	51.940504714 ± 0.00000012 Da
Mass Number	52
G-Factor	0
Half Life
Spin	0
Quadrupole Moment	0
Discovery Year	1923
Parity	+

⁵³Cr

Abundance	9.501 ± 0.017
Relative Atomic Mass	52.940646304 ± 0.000000124 Da
Mass Number	53
G-Factor
Half Life
Spin	3/2
Quadrupole Moment	-0.15 ± 0.05
Discovery Year	1930
Parity	-

⁵⁴Cr

Abundance	2.365 ± 0.007
Relative Atomic Mass	53.938877359 ± 0.000000142 Da
Mass Number	54
G-Factor	0
Half Life
Spin	0
Quadrupole Moment	0
Discovery Year	1930
Parity	+

⁵⁵Cr

Abundance	Radioactive ☢️
Relative Atomic Mass	54.940836637 ± 0.000000245 Da
Mass Number	55
G-Factor
Half Life	3.497 ± 0.003 m
Spin	3/2
Quadrupole Moment
Discovery Year	1952
Parity	-

⁵⁵Cr Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

⁵⁶Cr

Abundance	Radioactive ☢️
Relative Atomic Mass	55.940648977 ± 0.00000062 Da
Mass Number	56
G-Factor	0
Half Life	5.94 ± 0.1 m
Spin	0
Quadrupole Moment	0
Discovery Year	1960
Parity	+

⁵⁶Cr Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

⁵⁷Cr

Abundance	Radioactive ☢️
Relative Atomic Mass	56.943612112 ± 0.000002 Da
Mass Number	57
G-Factor
Half Life	21.1 ± 1 s
Spin	3/2
Quadrupole Moment
Discovery Year	1978
Parity

⁵⁷Cr Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

⁵⁸Cr

Abundance	Radioactive ☢️
Relative Atomic Mass	57.944184501 ± 0.0000032 Da
Mass Number	58
G-Factor	0
Half Life	7 ± 0.3 s
Spin	0
Quadrupole Moment	0
Discovery Year	1980
Parity	+

⁵⁸Cr Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

⁵⁹Cr

Abundance	Radioactive ☢️
Relative Atomic Mass	58.948345426 ± 0.00000072 Da
Mass Number	59
G-Factor
Half Life	1,050 ± 90 ms
Spin	1/2
Quadrupole Moment	0
Discovery Year	1980
Parity	-

⁵⁹Cr Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

⁶⁰Cr

Abundance	Radioactive ☢️
Relative Atomic Mass	59.949641656 ± 0.0000012 Da
Mass Number	60
G-Factor	0
Half Life	490 ± 10 ms
Spin	0
Quadrupole Moment	0
Discovery Year	1980
Parity	+

⁶⁰Cr Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	%

⁶¹Cr

Abundance	Radioactive ☢️
Relative Atomic Mass	60.95437813 ± 0.000002 Da
Mass Number	61
G-Factor
Half Life	243 ± 9 ms
Spin	5/2
Quadrupole Moment
Discovery Year	1985
Parity	-

⁶¹Cr Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	%

⁶²Cr

Abundance	Radioactive ☢️
Relative Atomic Mass	61.95614292 ± 0.0000037 Da
Mass Number	62
G-Factor	0
Half Life	206 ± 12 ms
Spin	0
Quadrupole Moment	0
Discovery Year	1985
Parity	+

⁶²Cr Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	%

⁶³Cr

Abundance	Radioactive ☢️
Relative Atomic Mass	62.961161 ± 0.000078 Da
Mass Number	63
G-Factor
Half Life	129 ± 2 ms
Spin	1/2
Quadrupole Moment	0
Discovery Year	1992
Parity	-

⁶³Cr Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	%

⁶⁴Cr

Abundance	Radioactive ☢️
Relative Atomic Mass	63.963886 ± 0.000322 Da
Mass Number	64
G-Factor	0
Half Life	43 ± 1 ms
Spin	0
Quadrupole Moment	0
Discovery Year	1992
Parity	+

⁶⁴Cr Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	%

⁶⁵Cr

Abundance	Radioactive ☢️
Relative Atomic Mass	64.969608 ± 0.000215 Da
Mass Number	65
G-Factor
Half Life	27.5 ± 2.1 ms
Spin	1/2
Quadrupole Moment	0
Discovery Year	1997
Parity	-

⁶⁵Cr Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	%
2n (2-neutron emission)	%

⁶⁶Cr

Abundance	Radioactive ☢️
Relative Atomic Mass	65.973011 ± 0.000322 Da
Mass Number	66
G-Factor	0
Half Life	23.8 ± 1.8 ms
Spin	0
Quadrupole Moment	0
Discovery Year	1997
Parity	+

⁶⁶Cr Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	%
2n (2-neutron emission)	%

⁶⁷Cr

Abundance	Radioactive ☢️
Relative Atomic Mass	66.979313 ± 0.000429 Da
Mass Number	67
G-Factor
Half Life
Spin	1/2
Quadrupole Moment	0
Discovery Year	1997
Parity	-

⁶⁷Cr Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	%
β⁻ n (β⁻-delayed neutron emission)	%
2n (2-neutron emission)	%

⁶⁸Cr

Abundance	Radioactive ☢️
Relative Atomic Mass	67.983156 ± 0.000537 Da
Mass Number	68
G-Factor	0
Half Life
Spin	0
Quadrupole Moment	0
Discovery Year	2009
Parity	+

⁶⁸Cr Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	%
β⁻ n (β⁻-delayed neutron emission)	%
2n (2-neutron emission)	%

⁶⁹Cr

Abundance	Radioactive ☢️
Relative Atomic Mass	68.989662 ± 0.000537 Da
Mass Number	69
G-Factor
Half Life
Spin	7/2
Quadrupole Moment
Discovery Year	2013
Parity	+

⁶⁹Cr Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	%
β⁻ n (β⁻-delayed neutron emission)	%
2n (2-neutron emission)	%

⁷⁰Cr

Abundance	Radioactive ☢️
Relative Atomic Mass	69.993945 ± 0.000644 Da
Mass Number	70
G-Factor	0
Half Life
Spin	0
Quadrupole Moment	0
Discovery Year	2013
Parity	+

⁷⁰Cr Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	%
β⁻ n (β⁻-delayed neutron emission)	%
2n (2-neutron emission)	%

History

In 1797, Louis Nicolas Vauquelin received samples of crocoite ore. In 1798, Vauquelin discovered that he could isolate metallic chromium by heating the oxide in a charcoal oven, making him the discoverer of the element. Vauquelin was also able to detect traces of chromium in precious gemstones, such as ruby or emerald. From the Greek word chroma, color

Discoverers	Louis Vauquelin
Discovery Location	France
Discovery Year	1797
Etymology (Name Origin)	Greek: chrôma (color).
Pronunciation	KROH-mi-em (English)

In larger amounts, chromium can be toxic and carcinogenic

Chromium oxide was used by the Chinese in the Qin dynasty over 2,000 years ago

Uses

Chromium is used to harden steel, manufacture stainless steel, and form many useful alloys. It is mostly used in plating to produce a hard, beautiful surface and to prevent corrosion. The metal is also widely used as a catalyst. Chromium compounds are valued as pigments for their vivid green, yellow, red and orange colors. Used to make stainless steel. It gives the color to rubies and emeralds. Iron-nickel-chromium alloys in various percentages yield an incredible variety of the most important metals in modern technology.

Sources

Chromite [Fe,Mg(CrO4)] is its most important mineral. Produced commercially by heating its ore in the presence of silicon or aluminium.

Abundance
Abundance in Earth's crust	102 mg/kg
Abundance in Oceans	0.0003 mg/L
Abundance in Human Body	0.000003 %
Abundance in Meteor	0.3 %
Abundance in Sun	0.002 %
Abundance in Universe	0.0015 %

Nuclear Screening Constants

1	s	0.5862
2	p	3.9248
2	s	7.0162
3	d	14.2434
3	p	12.534
3	s	11.6322
4	s	18.8668

Chromium on ChemicalAid

ASC Leiden Thesaurus ID	294904409
Art & Architecture Thesaurus ID	300011019
Australian Educational Vocabulary ID	scot/3730
BNCF Thesaurus ID	22189
Bibliothèque nationale de France ID	12104829h
Brockhaus Enzyklopädie online ID	chrom
CAS Registry Number	7440-47-3
Canadian Encyclopedia article ID	chromium
ChEBI ID	28073
DSSTOX compound identifier	DTXCID1011022
DSSTox substance ID	DTXSID3031022
DrugBank ID	11136
ECHA Substance Infocard ID	100.028.324
Encyclopedia of China ID (Second Edition)	204079
Encyclopædia Britannica Online ID	science/chromium
Encyclopædia Universalis ID	chrome
Europeana Fashion Vocabulary ID	10554
Freebase ID	/m/025tkr6
French Vikidia ID	Chrome
GND ID	4147944-0
Great Russian Encyclopedia Online ID	4671100
Grove Art Online ID	T017513
HSDB ID	910
ICSC ID	0029
IEDB Epitope ID	114071
InChI	InChI=1S/Cr
InChIKey	VYZAMTAEIAYCRO-UHFFFAOYSA-N
KBpedia ID	Chromium
KEGG ID	C06268
Krugosvet article	nauka_i_tehnika/himiya/HROM.html
Latvian National Encyclopedia Online ID	145861
Library of Congress authority ID	sh85025350
MeSH descriptor ID	D002857
Mindat mineral ID	1037
NDF-RT ID	N0000146088
NDL Authority ID	00567040
NE.se ID	cr-(krom)
NKCR AUT ID	ph119207
Namuwiki ID	크로뮴
National Library of Israel J9U ID	987007286324805171
OmegaWiki Defined Meaning	585
OpenAlex ID	C511782168
OpenAlex ID	C2909514155
PSH ID	5768
Pixiv Encyclopedia ID	クロム
Probes And Drugs ID	PD061009
PubChem CID	23976
Quora topic ID	Chromium-element
RKD thesaurus ID	92666
RxNorm ID	2496
STW Thesaurus for Economics ID	14295-6
Spanish Cultural Heritage thesauri ID	materias/1000922
Spanish Vikidia ID	Cromo
Store norske leksikon ID	krom
Treccani ID	cromo
U.S. National Archives Identifier	10646811
UK Archival Thesaurus ID	f2/mt225/4347/7866
UK Parliament thesaurus ID	9168
UNII	0R0008Q3JB
USGS Thesaurus ID	1429
WikiSkripta ID	12126
Wolfram Language entity code	Entity["Mineral", "Chromium"]
WordNet 3.1 Synset ID	14659270-n
YSO ID	20200
ZVG number	8190

Chromium (Cr)

Properties

Isotopes of Chromium

41Cr

41Cr Decay Modes

42Cr

42Cr Decay Modes

43Cr

43Cr Decay Modes

44Cr

44Cr Decay Modes

45Cr

45Cr Decay Modes

46Cr

46Cr Decay Modes

47Cr

47Cr Decay Modes

48Cr

48Cr Decay Modes

49Cr

49Cr Decay Modes

50Cr

50Cr Decay Modes

51Cr

51Cr Decay Modes

52Cr

53Cr

54Cr

55Cr

55Cr Decay Modes

56Cr

56Cr Decay Modes

57Cr

57Cr Decay Modes

58Cr

58Cr Decay Modes

59Cr

59Cr Decay Modes

60Cr

60Cr Decay Modes

61Cr

61Cr Decay Modes

62Cr

62Cr Decay Modes

63Cr

63Cr Decay Modes

64Cr

64Cr Decay Modes

65Cr

65Cr Decay Modes

66Cr

66Cr Decay Modes

67Cr

67Cr Decay Modes

68Cr

68Cr Decay Modes

69Cr

69Cr Decay Modes

70Cr

70Cr Decay Modes