Chromium, 24Cr
Chromium
Appearancesilvery metallic
Standard atomic weight Ar°(Cr)
Chromium in the periodic table
Hydrogen Helium
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Cr

Mo
vanadiumchromiummanganese
Atomic number (Z)24
Groupgroup 6
Periodperiod 4
Block  d-block
Electron configuration[Ar] 3d5 4s1
Electrons per shell2, 8, 13, 1
Physical properties
Phase at STPsolid
Melting point2180 K ​(1907 °C, ​3465 °F)
Boiling point2944 K ​(2671 °C, ​4840 °F)
Density (at 20° C)7.192 g/cm3[3]
when liquid (at m.p.)6.3 g/cm3
Heat of fusion21.0 kJ/mol
Heat of vaporization347 kJ/mol
Molar heat capacity23.35 J/(mol·K)
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 1656 1807 1991 2223 2530 2942
Atomic properties
Oxidation statescommon: +3, +6
−4,[4] −2,[5] −1,[5] 0,[6] +1,[5] +2,[5] +4,[5] +5[5]
ElectronegativityPauling scale: 1.66
Ionization energies
  • 1st: 652.9 kJ/mol
  • 2nd: 1590.6 kJ/mol
  • 3rd: 2987 kJ/mol
  • (more)
Atomic radiusempirical: 128 pm
Covalent radius139±5 pm
Color lines in a spectral range
Spectral lines of chromium
Other properties
Natural occurrenceprimordial
Crystal structurebody-centered cubic (bcc) (cI2)
Lattice constant
Body-centered cubic crystal structure for chromium
a = 288.49  pm (at 20 °C)[3]
Thermal expansion4.81×10−6/K (at 20 °C)[3]
Thermal conductivity93.9 W/(m⋅K)
Electrical resistivity125 nΩ⋅m (at 20 °C)
Magnetic orderingantiferromagnetic (rather: SDW)[7]
Molar magnetic susceptibility+280.0×10−6 cm3/mol (273 K)[8]
Young's modulus279 GPa
Shear modulus115 GPa
Bulk modulus160 GPa
Speed of sound thin rod5940 m/s (at 20 °C)
Poisson ratio0.21
Mohs hardness8.5
Vickers hardness1060 MPa
Brinell hardness687–6500 MPa
CAS Number7440-47-3
History
Discovery and first isolationLouis Nicolas Vauquelin (1794, 1797)
Isotopes of chromium
Main isotopes[9] Decay
abun­dance half-life (t1/2) mode pro­duct
50Cr 4.34% stable
51Cr synth 27.7025 d ε 51V
γ
52Cr 83.8% stable
53Cr 9.50% stable
54Cr 2.37% stable
 Category: Chromium
| references
Cr · Chromium
V ←

ibox V

iso
24
Cr  [e]
IB-Cr [e]
IBisos [e]
→ Mn

ibox Mn

indexes by PT (page)
child table, as reused in {IB-Cr}
Main isotopes of chromium
Main isotopes[9] Decay
abun­dance half-life (t1/2) mode pro­duct
50Cr 4.34% stable
51Cr synth 27.7025 d ε 51V
γ
52Cr 83.8% stable
53Cr 9.50% stable
54Cr 2.37% stable
Data sets read by {{Infobox element}}
Name and identifiers
Symbol etymology (11 non-trivial)
Top image (caption, alt)
Pronunciation
Allotropes (overview)
Group (overview)
Period (overview)
Block (overview)
Natural occurrence
Phase at STP
Oxidation states
Spectral lines image
Electron configuration (cmt, ref)
Isotopes
Standard atomic weight
  most stable isotope
Wikidata
Wikidata *
* Not used in {{Infobox element}} (2023-01-01)
See also {{Index of data sets}} · Cat:data sets (46) · (this table: )

References

  1. ^ "Standard Atomic Weights: Chromium". CIAAW. 1983.
  2. ^ Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
  3. ^ a b c Arblaster, John W. (2018). Selected Values of the Crystallographic Properties of Elements. Materials Park, Ohio: ASM International. ISBN 978-1-62708-155-9.
  4. ^ Cr(–4) is known in Na4Cr(CO)4; see John E. Ellis (2006). "Adventures with Substances Containing Metals in Negative Oxidation States". Inorganic Chemistry. 45 (8). doi:10.1021/ic052110i.
  5. ^ a b c d e f Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 28. ISBN 978-0-08-037941-8.
  6. ^ Cr(0) is known in Cr(CO)6; see John E. Ellis (2006). "Adventures with Substances Containing Metals in Negative Oxidation States". Inorganic Chemistry. 45 (8). doi:10.1021/ic052110i.
  7. ^ Fawcett, Eric (1988). "Spin-density-wave antiferromagnetism in chromium". Reviews of Modern Physics. 60: 209. Bibcode:1988RvMP...60..209F. doi:10.1103/RevModPhys.60.209.
  8. ^ Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN 0-8493-0464-4.
  9. ^ a b Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.