Cadmium

Cadmium - Cd

CAS: 7440-43-9
Description: Silvery-white metal
Classification: Transition Metal
Date of Discovery: 1817
Discoverer: Fredrich Stromeyer
Name Origin: Greek kadmeia, Latin cadmia; "calamine," zinc carbonate

Atomic Number: 48
Number of Neutrons: 64
Atomic Mass: 112.411(8) amu
Melting Point: 321.07 °C
Boiling Point: 767 °C
Density (293 K): 8.65 g/cm³
Atomic volume: 13.1 cm³/mol
Electrical resistivity: 0.138 10^-6/cm

Thermal conductivity: 0.968 W/cmK
Enthalpy of atomization: 113.0 kJ/mol
Enthalpy of vaporization: 99.570 kJ/mol
Enthalpy of fusion: 6.192 kJ/mol
Specific heat capacity: 0.23 J/gK

Energy levels: 2-8-18-18-2
Electron configuration: [Kr]4d¹⁰5s²
Crystal Structure: Hexagonal
Atomic radius: 1.71 Å
Covalent radius: 1.48 Å
Oxidation States: +2
Electronegativity, Pauling: 1.69
Electron affinity: not stable
First ionization energy: 8.993 eV
2nd ionization energy: 16.908 eV
3rd ionization energy: 37.48 eV
Polarizability: 7.2 10^-24cm³

Isotope	Natural Abundance	Atomic Mass	Half-life	Decay Mode	Spin
⁹⁷Cd	3 s	⁺, (p)
⁹⁸Cd	97.9276	9.2 s	⁺
⁹⁹Cd	98.9250	16 s	⁺, EC
¹⁰⁰Cd	99.9203	1.1 m	⁺, EC
¹⁰¹Cd	100.9187	1.2 m	⁺; EC	5/2+
¹⁰²Cd	101.91474	5.8 m	⁺; EC	0+
¹⁰³Cd	103.91342	7.5 m	⁺; EC	5/2+
¹⁰⁴Cd	103.90985	58 m	EC	0+
¹⁰⁵Cd	104.90947	55.5 m	⁺; EC	5/2+
¹⁰⁶Cd	1.25(4)	105.90646	Stable	0+
¹⁰⁷Cd	106.90661	6.52 m	EC; ⁺	5/2+
¹⁰⁸Cd	0.89(2)	107.90418	Stable	0+
¹⁰⁹Cd	108.904985	462.0 d	EC	5/2+
¹¹⁰Cd	12.49(12)	109.903006	Stable	0+
^111mCd	48.5 m	IT	11/2-
¹¹¹Cd	12.80(8)	110.904182	Stable	1/2+
¹¹²Cd	24.13(14)	111.902758	Stable	0+
^113mCd	14.1 y	^-	11/2-
¹¹³Cd	12.22(8)	112.904401	Stable	1/2+
¹¹⁴Cd	28.73(28)	113.903359	Stable	0+
^115mCd	44.6 d	^-	11/2-
¹¹⁵Cd	114.905431	2.228 d	^-	1/2+
¹¹⁶Cd	7.49(12)	115.904756	Stable	0+
^117mCd	3.4 h	^-	11/2-
¹¹⁷Cd	116.907219	2.49 h	^-	1/2+
¹¹⁸Cd	117.90692	50.3 m	^-	0+
^119mCd	2.20 m	^-	11/2-
¹¹⁹Cd	118.90992	2.69 m	^-	1/2+
¹²⁰Cd	119.90985	50.8 s	^-	0+
^121mCd	8 s	^-	11/2-
¹²¹Cd	120.9131	13.5 s	^-	(3/2+)
¹²²Cd	121.9135	5.3 s	^-	0+
^123mCd	1.9 s	^-	0+
¹²³Cd	122.91770	2.09 s	^-	3+
¹²⁴Cd	123.9177	1.24 s	^-	0+
¹²⁵Cd	0.66 s	^-
¹²⁵Cd	124.92129	0.68 s	^-	3/2+
¹²⁶Cd	125.9224	0.52 s	^-	0+
¹²⁷Cd	126.9264	0.4 s	^-	3/2+
¹²⁸Cd	127.9278	0.28 s	^-	0+
¹²⁹Cd	0.27 s	^-
¹³⁰Cd	0.20 s	^-
Discovered by Stromeyer in 1817 from an impurity in zinc carbonate. Cadmium most often occurs in small quantities associated with zinc ores, such as sphalerite (ZnS). Greenockite (CdS) is the only mineral of any consequence bearing cadmium. Almost all cadmium is obtained as a by-product in the treatment of zinc, copper, and lead ores. It is a soft, bluish-white metal which is easily cut with a knife. It is simililar in many respects to zinc. It is a component of some of the lowest melting alloys; it is used in bearing alloys with low coefficients of friction and great resistance to fatigue; it is used extensively in electroplating, which accounts for about 60% of its use. It is also used in many types of solder, for standard E.M.F. cells, for Ni-Cd batteries, and as a barrier to control atomic fission. Cadmium compounds are used in black and white television phosphors and in blue and green phosphors for color TV tubes. It forms a number of salts, of which the sulfate is most common; the sulfide is used as a yellow pigment. Cadmium and solutions of its compounds are toxic. Failure to appreciate the toxic properties of cadmium may cause workers to be unwittingly exposed to dangerous fumes. Some silver solders, for example, contain cadmium and should be handled with care. Serious toxicity problems have been found from long-term exposure and work with cadmium plating baths. In 1927 the International Conference on Weights and Measures redefined the meter in terms of the wavelength of the red cadmium spectral line (i.e. 1 in = 1,553,164.13 wavelengths). This definition has been changed (see under Krypton). Natural cadmium is made of eight isotopes. Thirty four other isotopes and isomers are now known and recognized. LINKS: AMM Online - Cadmium Profile ATSDR - ToxFAQs - Cadmium Cadmium Bioavailability Chemical Backgrounders - Cadmium Compton's Online: Cadmium EcoIndiana: Cadmium Uptake and Accumulation of Cadmium by Plants: Implications for Human Toxicity Working with Cadmium - Are You At Risk? Return Sources for the information on this website include: Lide, David R., ed. CRC Handbook of Chemistry and Physics, 78th Ed., 1997-1998.

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