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Cadmium - Cd General Information Discovery Cadmium was discovered by F. Stromeyer in 1817 in Göttingen, Germany, from an impurity in zinc carbonate. Appearance Cadmium is a soft, bluish-white metal which is easily cut with a knife. Source The only mineral containing significant quantities of cadmium is greenockite, although some is present in sphalerite. Almost all commercially produced cadmium is obtained as a by-product of the treatment of zinc, copper and lead ores. Uses Cadmium 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 nickel-cadmium batteries and in rods to control atomic fission. It is a component of some of the lowest melting alloys, alloys with low coefficients of friction, and alloys with great resistance to fatigue. Cadmium compounds are used in blue and green phosphors in colour television sets. Cadmium forms a number of compounds, the sulfide being used as an artist's pigment as it is bright yellow. Biological Role Cadmium is toxic, carcinogenic and teratogenic. In the past, failure to recognise the toxicity of this element caused workers to be exposed to danger in the form of solder fumes and cadmium plating baths. General Information Cadmium tarnishes in air, and is soluble in acids but not in alkalis. |
| Physical Information | |||
| Atomic Number | 48 | ||
| Relative Atomic Mass (12C=12.000) | 112.41 | ||
| Melting Point/K | 594 | ||
| Boiling Point/K | 1038 | ||
| Density/kg m-3 | 8650 (293K) | ||
| Ground State Electron Configuration | [Kr]4d105s2 | ||
| Electron Affinity(M-M-)/kJ mol-1 | +26 |
| Key Isotopes | ||||||
| nuclide | 106Cd | 108Cd | 109Cd | 110Cd | 111Cd | |
| atomic mass | 105.91 | 107.9 | 109.9 | 110.9 | ||
| natural abundance | 1.25% | 0.89% | 0% | 12.51% | 12.81% | |
| half-life | stable | stable | 450 days | stable | stable | |
| nuclide | 112Cd | 113Cd | 114Cd | 115Cd | 116Cd | |
| atomic mass | 111.9 | 112.9 | 113.9 | 115.9 | ||
| natural abundance | 24.13% | 12.22% | 28.72% | 0% | 7.47% | |
| half-life | stable | stable | stable | 53.5 hrs | stable | |
| Other Information | ||
| Enthalpy of Fusion/kJ mol-1 | 6.11 | |
| Enthalpy of Vaporisation/kJ mol-1 | 100 | |
| Oxidation States | ||
| main | Cd+2 | |
| others | Cd+1 | |
| Ionisation Energies/kJ mol-1 | ||
| M - M+ | 867.6 | |
| M+ - M2+ | 1631 | |
| M2+ - M3+ | 3616 | |
| M3+ - M4+ | 5300 | |
| M4+ - M5+ | 7000 | |
| M5+ - M6+ | 9100 | |
| M6+ - M7+ | 11100 | |
| M7+ - M8+ | 14100 | |
| M8+ - M9+ | 16400 | |
| M9+ - M10+ | 18800 | |
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