Chromium

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 Number24
Atomic Weight51.9961
Mass Number52
Group6
Period4
Blockd
Protons24 p+
Neutrons28 n0
Electrons24 e-
Animated Bohr Model of Cr (Chromium)

Physical Properties

Atomic Radius
140 pm
Molar Volume
Covalent Radius
122 pm
Metallic Radius
119 pm
Ionic Radius
73 pm
Crystal Radius
87 pm
Van der Waals Radius
206 pm
Density
7.15 g/cm³
Atomic Radii of the Elements: Chromium0102030405060708090100110120130140150160170180190200210pmAtomic RadiusCovalent RadiusMetallic RadiusVan der Waals Radius

Chemical Properties

Energy
Proton Affinity
791.3 kJ/mol
Electron Affinity
Ionization Energy
6.76651 eV/particle
Ionization Energies of Cr (Chromium)
Heat of Vaporization
342 kJ/mol
Heat of Fusion
Heat of Formation
397.48 kJ/mol
Electrons
Electron Shells2, 8, 13, 1
Bohr Model: Cr (Chromium)
Valence Electrons1
Lewis Structure: Cr (Chromium)
Electron Configuration[Ar] 3d5 4s1
1s2 2s2 2p6 3s2 3p6 3d5 4s1
Enhanced Bohr Model of Cr (Chromium)
Orbital Diagram of Cr (Chromium)
Oxidation States-4, -2, -1, 0, 1, 2, 3, 4, 5, 6
Electronegativity
1.66
Electrophilicity Index
1.1319177597467263 eV/particle
States of Matter
PhaseSolid
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
Appearancesilvery 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
TypeConductor
Electrical Conductivity
7.9 MS/m
Electrical Resistivity
0.00000013 m Ω
Superconducting Point
Magnetism
Typeantiferromagnetic
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 StructureBody Centered Cubic (BCC)
Lattice Constant
2.88 Å
Lattice Anglesπ/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
8.5 MPa
Bulk Modulus
160 GPa
Shear Modulus
115 GPa
Young's 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.

CategoryTransition metals, Transition metals
CAS GroupVIA
IUPAC GroupVIB
Glawe Number55
Mendeleev Number51
Pettifor Number57
Geochemical Classfirst series transition metal
Goldschmidt Classlitophile

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
Allotropes
Neutron Cross Section
3.1
Neutron Mass Absorption
0.0021
Quantum Numbers7S3
Space Group229 (Im_3m)

Isotopes of Chromium

Stable Isotopes3
Unstable Isotopes27
Natural Isotopes4
Isotopic Composition5283.79%5283.79%539.50%539.50%504.35%504.35%542.37%542.37%

41Cr

Mass Number41
Neutron Number17
Relative Atomic Mass
41.021911 ± 0.000429 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
Spin3/2
Quadrupole Moment
Discovery Year
Parity+

Decay ModeIntensity
p (proton emission)

42Cr

Mass Number42
Neutron Number18
Relative Atomic Mass
42.007579 ± 0.000322 Da
G-Factor
0
Abundance
Radioactivity☢️ Radioactive
Half Life
13.3 ± 1 ms
Spin0
Quadrupole Moment
0
Discovery Year1996
Parity+

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

43Cr

Mass Number43
Neutron Number19
Relative Atomic Mass
42.997885 ± 0.000215 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
21.1 ± 0.3 ms
Spin3/2
Quadrupole Moment
Discovery Year1992
Parity+

Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)79.3%
2p (2-proton emission)11.6%
3p0.13%
β+α (β+-delayed α emission)

44Cr

Mass Number44
Neutron Number20
Relative Atomic Mass
43.985591 ± 0.000055 Da
G-Factor
0
Abundance
Radioactivity☢️ Radioactive
Half Life
42.8 ± 0.6 ms
Spin0
Quadrupole Moment
0
Discovery Year1987
Parity+

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

45Cr

Mass Number45
Neutron Number21
Relative Atomic Mass
44.97905 ± 0.000038 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
60.9 ± 0.4 ms
Spin7/2
Quadrupole Moment
Discovery Year1974
Parity-

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

46Cr

Mass Number46
Neutron Number22
Relative Atomic Mass
45.968360969 ± 0.000012295 Da
G-Factor
0
Abundance
Radioactivity☢️ Radioactive
Half Life
224.3 ± 1.3 ms
Spin0
Quadrupole Moment
0
Discovery Year1972
Parity+

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

47Cr

Mass Number47
Neutron Number23
Relative Atomic Mass
46.962894995 ± 0.000005578 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
461.6 ± 1.5 ms
Spin3/2
Quadrupole Moment
Discovery Year1972
Parity-

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

48Cr

Mass Number48
Neutron Number24
Relative Atomic Mass
47.954029431 ± 0.000007848 Da
G-Factor
0
Abundance
Radioactivity☢️ Radioactive
Half Life
21.56 ± 0.03 h
Spin0
Quadrupole Moment
0
Discovery Year1952
Parity+

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

49Cr

Mass Number49
Neutron Number25
Relative Atomic Mass
48.95133372 ± 0.000002363 Da
G-Factor
0.1904 ± 0.0012
Abundance
Radioactivity☢️ Radioactive
Half Life
42.3 ± 0.1 m
Spin5/2
Quadrupole Moment
Discovery Year1942
Parity-

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

50Cr

Mass Number50
Neutron Number26
Relative Atomic Mass
49.946042209 ± 0.0000001 Da
G-Factor
0
Abundance
4.345 ± 0.013
Radioactivity☢️ Radioactive
Half Life
Spin0
Quadrupole Moment
0
Discovery Year1930
Parity+

Decay ModeIntensity
+ (double β+ decay)

51Cr

Mass Number51
Neutron Number27
Relative Atomic Mass
50.944765388 ± 0.000000178 Da
G-Factor
0.26685714285714 ± 0.0014285714285714
Abundance
Radioactivity☢️ Radioactive
Half Life
27.7015 ± 0.0011 d
Spin7/2
Quadrupole Moment
Discovery Year1940
Parity-

Decay ModeIntensity
ϵ (electron capture)100%

52Cr

Mass Number52
Neutron Number28
Relative Atomic Mass
51.940504714 ± 0.00000012 Da
G-Factor
0
Abundance
83.789 ± 0.018
RadioactivityStable
Half LifeNot Radioactive ☢️
Spin0
Quadrupole Moment
0
Discovery Year1923
Parity+

53Cr

Mass Number53
Neutron Number29
Relative Atomic Mass
52.940646304 ± 0.000000124 Da
G-Factor
Abundance
9.501 ± 0.017
RadioactivityStable
Half LifeNot Radioactive ☢️
Spin3/2
Quadrupole Moment
-0.15 ± 0.05
Discovery Year1930
Parity-

54Cr

Mass Number54
Neutron Number30
Relative Atomic Mass
53.938877359 ± 0.000000142 Da
G-Factor
0
Abundance
2.365 ± 0.007
RadioactivityStable
Half LifeNot Radioactive ☢️
Spin0
Quadrupole Moment
0
Discovery Year1930
Parity+

55Cr

Mass Number55
Neutron Number31
Relative Atomic Mass
54.940836637 ± 0.000000245 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
3.497 ± 0.003 m
Spin3/2
Quadrupole Moment
Discovery Year1952
Parity-

Decay ModeIntensity
β (β decay)100%

56Cr

Mass Number56
Neutron Number32
Relative Atomic Mass
55.940648977 ± 0.00000062 Da
G-Factor
0
Abundance
Radioactivity☢️ Radioactive
Half Life
5.94 ± 0.1 m
Spin0
Quadrupole Moment
0
Discovery Year1960
Parity+

Decay ModeIntensity
β (β decay)100%

57Cr

Mass Number57
Neutron Number33
Relative Atomic Mass
56.943612112 ± 0.000002 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
21.1 ± 1 s
Spin3/2
Quadrupole Moment
Discovery Year1978
Parity

Decay ModeIntensity
β (β decay)100%

58Cr

Mass Number58
Neutron Number34
Relative Atomic Mass
57.944184501 ± 0.0000032 Da
G-Factor
0
Abundance
Radioactivity☢️ Radioactive
Half Life
7 ± 0.3 s
Spin0
Quadrupole Moment
0
Discovery Year1980
Parity+

Decay ModeIntensity
β (β decay)100%

59Cr

Mass Number59
Neutron Number35
Relative Atomic Mass
58.948345426 ± 0.00000072 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
1,050 ± 90 ms
Spin1/2
Quadrupole Moment
0
Discovery Year1980
Parity-

Decay ModeIntensity
β (β decay)100%

60Cr

Mass Number60
Neutron Number36
Relative Atomic Mass
59.949641656 ± 0.0000012 Da
G-Factor
0
Abundance
Radioactivity☢️ Radioactive
Half Life
490 ± 10 ms
Spin0
Quadrupole Moment
0
Discovery Year1980
Parity+

Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)

61Cr

Mass Number61
Neutron Number37
Relative Atomic Mass
60.95437813 ± 0.000002 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
243 ± 9 ms
Spin5/2
Quadrupole Moment
Discovery Year1985
Parity-

Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)

62Cr

Mass Number62
Neutron Number38
Relative Atomic Mass
61.95614292 ± 0.0000037 Da
G-Factor
0
Abundance
Radioactivity☢️ Radioactive
Half Life
206 ± 12 ms
Spin0
Quadrupole Moment
0
Discovery Year1985
Parity+

Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)

63Cr

Mass Number63
Neutron Number39
Relative Atomic Mass
62.961161 ± 0.000078 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
129 ± 2 ms
Spin1/2
Quadrupole Moment
0
Discovery Year1992
Parity-

Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)

64Cr

Mass Number64
Neutron Number40
Relative Atomic Mass
63.963886 ± 0.000322 Da
G-Factor
0
Abundance
Radioactivity☢️ Radioactive
Half Life
43 ± 1 ms
Spin0
Quadrupole Moment
0
Discovery Year1992
Parity+

Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)

65Cr

Mass Number65
Neutron Number41
Relative Atomic Mass
64.969608 ± 0.000215 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
27.5 ± 2.1 ms
Spin1/2
Quadrupole Moment
0
Discovery Year1997
Parity-

Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)
2n (2-neutron emission)

66Cr

Mass Number66
Neutron Number42
Relative Atomic Mass
65.973011 ± 0.000322 Da
G-Factor
0
Abundance
Radioactivity☢️ Radioactive
Half Life
23.8 ± 1.8 ms
Spin0
Quadrupole Moment
0
Discovery Year1997
Parity+

Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)
2n (2-neutron emission)

67Cr

Mass Number67
Neutron Number43
Relative Atomic Mass
66.979313 ± 0.000429 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
Spin1/2
Quadrupole Moment
0
Discovery Year1997
Parity-

Decay ModeIntensity
β (β decay)
β n (β-delayed neutron emission)
2n (2-neutron emission)

68Cr

Mass Number68
Neutron Number44
Relative Atomic Mass
67.983156 ± 0.000537 Da
G-Factor
0
Abundance
Radioactivity☢️ Radioactive
Half Life
Spin0
Quadrupole Moment
0
Discovery Year2009
Parity+

Decay ModeIntensity
β (β decay)
β n (β-delayed neutron emission)
2n (2-neutron emission)

69Cr

Mass Number69
Neutron Number45
Relative Atomic Mass
68.989662 ± 0.000537 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
Spin7/2
Quadrupole Moment
Discovery Year2013
Parity+

Decay ModeIntensity
β (β decay)
β n (β-delayed neutron emission)
2n (2-neutron emission)

70Cr

Mass Number70
Neutron Number46
Relative Atomic Mass
69.993945 ± 0.000644 Da
G-Factor
0
Abundance
Radioactivity☢️ Radioactive
Half Life
Spin0
Quadrupole Moment
0
Discovery Year2013
Parity+

Decay ModeIntensity
β (β decay)
β n (β-delayed neutron emission)
2n (2-neutron emission)
Chromium crystals and 1cm3 cube

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

DiscoverersLouis Vauquelin
Discovery LocationFrance
Discovery Year1797
Etymology (Name Origin)Greek: chrôma (color).
PronunciationKROH-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
Natural Abundance (Oceans)
0.0003 mg/L
Natural Abundance (Human Body)
0.000003 %
Natural Abundance (Meteor)
0.3 %
Natural Abundance (Sun)
0.002 %
Abundance in Universe
0.0015 %

Nuclear Screening Constants

1s0.5862
2p3.9248
2s7.0162
3d14.2434
3p12.534
3s11.6322
4s18.8668

Also Known As

  • Cr
  • element 24
  • 24Cr

Translations

  • Italiancromo
  • Norwegian Bokmålkrom
  • GermanChrom
  • Frenchchrome
  • Dutchchroom
  • Spanishcromo
  • Chinese (Traditional)
  • Afrikaanschroom
  • Amharicክሮሚየም
  • AragoneseCromo
  • Arabicكروم
  • AsturianCromu
  • AzerbaijaniXrom
  • BelarusianХром
  • Bulgarianхром
  • Banglaক্রোমিয়াম
  • BretonKrom
  • Bosnianhrom
  • Catalancrom
  • CorsicanCromu
  • Czechchrom
  • ChuvashХром
  • WelshCromiwm
  • Danishkrom
  • Divehiކްރޯމިއަމް
  • Greekχρώμιο
  • Esperantokromo
  • Estoniankroom
  • Basquekromo
  • Persianکروم
  • Finnishkromi
  • FriulianCrom
  • IrishCróimiam
  • Galiciancromo
  • Manxcromium
  • Hakka Chinesechromium
  • Hebrewכרום
  • Hindiक्रोमियम
  • Fiji HindiChromium
  • Croatiankrom
  • Upper SorbianChrom
  • Haitian CreoleKwòm
  • Hungariankróm
  • Armenianքրոմ
  • Interlinguachromo
  • Indonesiankromium
  • Idokromo
  • Icelandickróm
  • Japaneseクロム
  • Lojbanrogjinme
  • Georgianქრომი
  • Kannadaಕ್ರೋಮಿಯಮ್
  • Korean크로뮴
  • KurdishKrom
  • KomiХром
  • Latinchromium
  • LuxembourgishChrom
  • LigurianCrommo
  • Lithuanianchromas
  • Latvianhroms
  • Māorikonukita
  • Macedonianхром
  • Malayalamക്രോമിയം
  • Mongolianхром
  • Marathiक्रोमियम
  • Western MariХром
  • MalayKromium
  • Burmeseခရိုမီယမ်
  • nahTlapāltepoztli
  • Low GermanChrom
  • Norwegian Nynorskkrom
  • OccitanCròme
  • Punjabiਕ੍ਰੋਮੀਅਮ
  • Polishchrom
  • Western Panjabiکرومیم
  • Portuguesecromo
  • QuechuaKrumu
  • Romaniancrom
  • Russianхром
  • Siciliancromu
  • Serbo-CroatianHrom
  • Slovakchróm
  • Sloveniankrom
  • AlbanianKromi
  • Serbianхром
  • Saterland FrisianChrom
  • Swedishkrom
  • SwahiliChromi
  • Tamilகுரோமியம்
  • Teluguక్రోమియం
  • Thaiโครเมียม
  • Turkishkrom
  • Uyghurخروم
  • Ukrainianхром
  • UzbekXrom
  • VepsHrom
  • Vietnamesechromi
  • WarayCromo
  • KalmykХром
  • Yiddishכראם
  • YorubaKrómíọ̀mù
  • Chinese
  • English (Canada)chromium
  • English (United Kingdom)chromium
  • Portuguese (Brazil)cromo
  • Cantonese
  • KazakhХром
  • TagalogKromyo
  • CebuanoKromyo
  • Central Kurdishکرۆم
  • Northern FrisianKroom
  • Odiaକ୍ରୋମିୟମ
  • Gujaratiક્રોમિયમ
  • PiedmonteseCròm
  • TatarХром
  • Scotschromium
  • Newariक्रोमियम
  • Literary Chinese
  • Belarusian (Taraskievica orthography)Хром
  • ErzyaХром
  • SomaliKoroomiyaam
  • German (Austria)Chrom
  • German (Switzerland)Chrom
  • Chinese (Hong Kong SAR China)
  • Chinese (Taiwan)
  • Chinese (China)
  • Chinese (Simplified)
  • AromanianCromu
  • Sanskritक्रोमियम
  • KyrgyzХром
  • SardinianCromu
  • LimburgishChroeam
  • cdoGáuk
  • FaroeseKrom
  • LombardCróm
  • Maltesekromju
  • Nepaliक्रोमियम
  • Paliक्रोमियम
  • Min Nan ChineseChromium
  • Bhojpuriक्रोमियम
  • Tibetanཀོ་ལྕགས།
  • SundaneseKromium
  • Lingua Franca Novacromo
  • oloHrom
  • Wu Chinese
  • Urduکرومیئم
  • kbpKurom
  • TajikХром
  • JavaneseKromiyum
  • BavarianChrom
  • Scottish GaelicCròmium
  • KotavaVogel
  • Moroccan Arabicكروم
  • Egyptian Arabicكروم
  • Pashtoکروميم
  • lldCrom
  • CornishKromiom
  • BikolKromyo
  • MinangkabauKromium
  • BalineseKromium
  • GandaKolomiyaamu
  • MalagasyKrômia
  • blkခရိုမီယမ်
  • ZuluUmChiyangqwala