Cadmium is a soft, bluish-white metal and is easily cut with a knife. It is similar in many respects to zinc. Interestingly, aa characteristic cadmium "scream" is heard on bending a cadmium bar (such as that illustrated above). Cadmium and its compounds are highly toxic. Silver solder, which contains cadmium, should be handled with care.
Cadmium might be a necessary element in very, very, small quantities in rats.
Inhalation of cadmium dust causes problems for the respiratory tract and for the kidneys. Death may follow. Ingestion of any significant amount of cadmium causes immediate poisoning and damage to the liver and the kidneys.
Cadmium wasdiscovered by Friedrich Strohmeyer in 1817 at Germany.Origin of name: somewhat confusingly, from the Latin word "cadmia" meaning "calamine" (zinc carbonate, ZnCO3) and from the Greek word "kadmeia" with the same meaning..
Isotope abundances of cadmium with the most intense signal set to 100%.
The nine stable Cadmium isotopes are used for many different purposes. Cd-110 is used for the production of the radioisotope In-110, while Cd-112 is used in the production of the widely used diagnostic radioisotope In-111. Cd-108 is used in the production of Cd-109 which is a calibration source for 88 keV gamma radiation. The even numbered Cd isotopes (mainly Cd-110, Cd-112, Cd-114 and Cd-116) are used to improve the power output and coherence length of HeCd lasers.
Isolation: it is rare that preparation of cadmium in the laboratory should be required bacause of environmental concerns about cadmium. The isolation of cadmium is associated with zinc recovery as cadmium is an impurity in zinc ores. Most zinc production is based upon sulphide ores. These are roasted in industrial plants to form zinc oxide, ZnO. This may be reduced with carbon to form zinc metal, but in practice ingenious technology is required to ensure that the resulting zinc does not contain oxide impurities.
ZnO + C → Zn + CO
ZnO + CO → Zn + CO2
CO2 + C → 2CO
After this process, zinc may be refined by distillation under vacuum and this process also allows the separation of any cadmium present in the crude zinc.
The other type of extraction of zinc is electrolytic. Dissolution of crude zinc oxide, ZnO, in sulphuric acid gives zinc sulphate, ZnSO4 in solution. Before electrolysis to produce zinc, the cadmium impurity and is removed as a precipitate by the addition of zinc dust as cadmium sulphate.
Density of solid: 8650 kg m-3
Molar volume: 13.00 cm3
Thermal conductivity: 97 W m‑1 K‑1
Melting point: 594.22 [321.07 °C (609.93 °F)] K
Boiling point: 1040 [767 °C (1413 °F)] K
Enthalpy of fusion: 20.5 kJ mol-1
Atomic radius (empirical): 155 pm
Molecular single bond covalent radius: 136 (coordination number 1) ppm
van der Waals radius: 249 ppm
Pauling electronegativity: 1.69 (Pauling units)
Allred Rochow electronegativity: 1.46 (Pauling units)
Mulliken-Jaffe electronegativity: 1.53 (sp orbital)
First ionisation energy: 867.77 kJ mol‑1
Second ionisation energy: 1631.40 kJ mol‑1
Third ionisation energy: 3615.1 kJ mol‑1
Universe: 2 ppb by weight
Crustal rocks: 150 ppb by weight
Human: 700 ppb by weight
