Stable isotopes of cadmium available from ISOFLEX
|Isotope||Z(p)||N(n)||Atomic Mass||Natural Abundance||Enrichment Level||Chemical Form|
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Cadmium was discovered in 1817 by Friedrich Strohmeyer. Its name originates with the Latin word cadmia (meaning "calamine" or "zinc carbonate") as well as the Greek word kadmeia, with the same meaning.
Cadmium is a bluish-white lustrous soft metal with a close-packed hexagonal system. It is insoluble in water. The metal is slowly oxidized in moist air at ordinary temperatures, forming a protective coating of cadmium oxide. The element combines with many nonmetals upon heating, forming its binary salts. It combines with halogens when heated, forming the corresponding halides. The metal is attacked by mineral acids. Reactions with hot dilute nitric acid give various oxides of nitrogen and hydrogen. Aqueous solutions of alkali hydroxides do not attack cadmium.
Cadmium replaces elements that are less electropositive in the activity series from their salt solutions. It can displace a number of metals that are less active, such as copper, lead, silver, mercury, tin and antimony from their aqueous salt solutions. It is used for electroplating, to impart a protective coating on iron and steel. It provides resistance against caustic alkalis.
A major application is in the nickel-cadmium storage battery, where it enhances long service life and a wide operating range. Cadmium alloys also find wide applications in bearing metals, solders, fusible metals, electrical conductors, power transmission wires and jewelry. Cadmium electrodes are used in photoelectric cells, cadmium vapor lamps and selenium rectifiers. Graphite impregnated with cadmium is used in electrical controller switches, oil-less bearings and busing lines. Cadmium rods are used in nuclear reactors to absorb low-energy neutrons.
Properties of Cadmium
|Standard state||Solid at 298 °K|
|CAS Registry ID||7440-43-9|
|Group in periodic table||12|
|Period in periodic table||5|
|Block in periodic table||d-block|
|Color||Silvery gray metallic|
|Melting point||321.1 °C|
|Boiling point||765 °C|
|Vaporization point||767 °C|
|Thermal conductivity||97 W/(m·K)|
|Electrical resistivity||6.83 µΩ·cm at 0 °C|
|Specific heat||230 J/(kg·K)|
|Heat of vaporization||100 kJ·mol-1|
|Heat of fusion||6.3 kJ·mol-1|
|Density of liquid||7.996 g/cm3 at 321.1 °C|
|Density of solid||8.65 g/cm3|
|Ionization potential||8.994 eV|
|Standard electrode potential||Eº = -0.40 V|