Cadmium

Cadmium, ₄₈Cd
Cadmium
Pronunciation	/ˈkædmiəm/ (KAD-mee-əm)
Appearance	silvery bluish-gray metallic
Standard atomic weight Ar°(Cd)
	112.414±0.004; 112.41±0.01 (abridged);
Cadmium in the periodic table
	silver ← cadmium → indium
Atomic number (Z)	48
Group	group 12
Period	period 5
Block	d-block
Electron configuration	[Kr] 4d10 5s2
Electrons per shell	2, 8, 18, 18, 2
Physical properties
Phase at STP	solid
Melting point	594.22 K (321.07 °C, 609.93 °F)
Boiling point	1040 K (767 °C, 1413 °F)
Density (at 20° C)	8.649 g/cm3
when liquid (at m.p.)	7.996 g/cm3
Heat of fusion	6.21 kJ/mol
Heat of vaporization	99.87 kJ/mol
Molar heat capacity	26.020 J/(mol·K)
Atomic properties
Oxidation states	common: +2; −2, +1
Electronegativity	Pauling scale: 1.69
Ionization energies	1st: 867.8 kJ/mol ; 2nd: 1631.4 kJ/mol ; 3rd: 3616 kJ/mol ; ;
Atomic radius	empirical: 151 pm
Covalent radius	144±9 pm
Van der Waals radius	158 pm
	Spectral lines of cadmium
Other properties
Natural occurrence	primordial
Crystal structure	hexagonal close-packed (hcp) (hP2)
Lattice constants	a = 297.89 pm; c = 561.66 pm (at 20 °C)
Thermal expansion	30.95×10−6/K (at 20 °C)
Thermal conductivity	96.6 W/(m⋅K)
Electrical resistivity	72.7 nΩ⋅m (at 22 °C)
Magnetic ordering	diamagnetic
Molar magnetic susceptibility	−19.8×10−6 cm3/mol
Young's modulus	50 GPa
Shear modulus	19 GPa
Bulk modulus	42 GPa
Speed of sound thin rod	2310 m/s (at 20 °C)
Poisson ratio	0.30
Mohs hardness	2.0
Brinell hardness	203–220 MPa
CAS Number	7440-43-9
History
Discovery and first isolation	Karl Samuel Leberecht Hermann and Friedrich Stromeyer (1817)
Named by	Friedrich Stromeyer (1817)
Isotopes of cadmium v; e;
IT	113Cd
	Category: Cadmium; view; talk; edit; \| references

Cadmium is a chemical element; it has symbol Cd and atomic number 48. This soft, silvery-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Like zinc, it demonstrates oxidation state +2 in most of its compounds, and like mercury, it has a lower melting point than the transition metals in groups 3 through 11. Cadmium and its congeners in group 12 are often not considered transition metals, in that they do not have partly filled d or f electron shells in the elemental or common oxidation states. The average concentration of cadmium in Earth's crust is between 0.1 and 0.5 parts per million (ppm). It was discovered in 1817 simultaneously by Stromeyer and Hermann, both in Germany, as an impurity in zinc carbonate.

Cadmium occurs as a minor component in most zinc ores and is a byproduct of zinc production. It was used for a long time in the 1900s as a corrosion-resistant plating on steel, and cadmium compounds are used as red, orange, and yellow pigments, to color glass, and to stabilize plastic. Cadmium's use is generally decreasing because it is toxic (it is specifically listed in the European Restriction of Hazardous Substances Directive^[9]) and nickel–cadmium batteries have been replaced with nickel–metal hydride and lithium-ion batteries. Due to it being a neutron poison, cadmium is also used as a component of control rods in nuclear fission reactors. One of its few new uses is in cadmium telluride solar panels.

Although cadmium has no known biological function in higher organisms, a cadmium-dependent carbonic anhydrase has been found in marine diatoms.

^ "Standard Atomic Weights: Cadmium". CIAAW. 2013.
^ 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. (4 May 2022). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
^ ^a ^b ^c ^d Arblaster, John W. (2018). Selected Values of the Crystallographic Properties of Elements. Materials Park, Ohio: ASM International. ISBN 978-1-62708-155-9.
^ Cd(−2) have been observed (as dimeric and monomeric anions; dimeric ions were initially reported to be [T–T]²⁻, but later shown to be [T–T]⁴⁻) in Sr₅Cd₃; see Changhoon Lee; Myung-Hwan Whangbo; Jürgen Köhler (2010). "Analysis of Electronic Structures and Chemical Bonding of Metal-rich Compounds. 2. Presence of Dimer (T–T)^4– and Isolated T^2– Anions in the Polar Intermetallic Cr₅B₃-Type Compounds AE₅T₃ (AE = Ca, Sr; T = Au, Ag, Hg, Cd, Zn)". Zeitschrift für Anorganische und Allgemeine Chemie. 636 (1): 36–40. doi:10.1002/zaac.200900421.
^ Cd(I) has been observed in cadmium(I) tetrachloroaluminate (Cd₂(AlCl₄)₂); see Holleman, Arnold F.; Wiberg, Egon; Wiberg, Nils (1985). "Cadmium". Lehrbuch der Anorganischen Chemie (in German) (91–100 ed.). Walter de Gruyter. pp. 1056–1057. ISBN 978-3-11-007511-3.
^ Lide, D. R., ed. (2005). "Magnetic susceptibility of the elements and inorganic compounds". CRC Handbook of Chemistry and Physics (PDF) (86th ed.). Boca Raton (FL): CRC Press. ISBN 0-8493-0486-5.
^ Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN 0-8493-0464-4.
^ 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.
^ Morrow, H. (2010). "Cadmium and Cadmium Alloys". Kirk-Othmer Encyclopedia of Chemical Technology. John Wiley & Sons. pp. 1–36. doi:10.1002/0471238961.0301041303011818.a01.pub3. ISBN 978-0-471-23896-6.

Cite error: There are <ref group=lower-alpha> tags or {{efn}} templates on this page, but the references will not show without a {{reflist|group=lower-alpha}} template or {{notelist}} template (see the help page).

[1] "Standard Atomic Weights: Cadmium". CIAAW. 2013.

[CIAAW2021-2] 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. (4 May 2022). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.

[Arblaster_2018-3] Arblaster, John W. (2018). Selected Values of the Crystallographic Properties of Elements. Materials Park, Ohio: ASM International. ISBN 978-1-62708-155-9.

[MetalAnions-4] Cd(−2) have been observed (as dimeric and monomeric anions; dimeric ions were initially reported to be [T–T]²⁻, but later shown to be [T–T]⁴⁻) in Sr₅Cd₃; see Changhoon Lee; Myung-Hwan Whangbo; Jürgen Köhler (2010). "Analysis of Electronic Structures and Chemical Bonding of Metal-rich Compounds. 2. Presence of Dimer (T–T)^4– and Isolated T^2– Anions in the Polar Intermetallic Cr₅B₃-Type Compounds AE₅T₃ (AE = Ca, Sr; T = Au, Ag, Hg, Cd, Zn)". Zeitschrift für Anorganische und Allgemeine Chemie. 636 (1): 36–40. doi:10.1002/zaac.200900421.

[5] Cd(I) has been observed in cadmium(I) tetrachloroaluminate (Cd₂(AlCl₄)₂); see Holleman, Arnold F.; Wiberg, Egon; Wiberg, Nils (1985). "Cadmium". Lehrbuch der Anorganischen Chemie (in German) (91–100 ed.). Walter de Gruyter. pp. 1056–1057. ISBN 978-3-11-007511-3.

[7] Lide, D. R., ed. (2005). "Magnetic susceptibility of the elements and inorganic compounds". CRC Handbook of Chemistry and Physics (PDF) (86th ed.). Boca Raton (FL): CRC Press. ISBN 0-8493-0486-5.

[8] Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN 0-8493-0464-4.

[NUBASE2020-9] 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.

[ReferenceA-10] Morrow, H. (2010). "Cadmium and Cadmium Alloys". Kirk-Othmer Encyclopedia of Chemical Technology. John Wiley & Sons. pp. 1–36. doi:10.1002/0471238961.0301041303011818.a01.pub3. ISBN 978-0-471-23896-6.

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