Symbol: K
Atomic Number: 19
Boiling Point: 1033 K
Melting Point: 336.8 K
Density at 300K: 0.86 g/cm3
Covalent radius: 2.03
Atomic radius: 2.77
Atomic volume: 45.30 cm3/mol
First ionization potental: 4.341 V
Specific heat capacity: 0.757 Jg-1K-1
Thermal conductivity: 102.5 Wm-1K-1
Electrical conductivity: 16.4 106Ω-1m-1
Heat of fusion: 2.33 kJ/mol
Heat of vaporization: 76.9 kJ/mol
Electronegativity: 0.82 (Pauling's)

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(So named (Dutch: potasch, "potash") in 1807 by Humphry Davy, who first isolated it from potash) A soft, silver-white, waxlike metallic chemical element, one of the alkali metals, that oxidizes rapidly when exposed to air. It occurs abudantly in nature in the form of its salts, which are used primarily in fertilizers. Potassium compounds are also used in making explosives, in making soaps and detergents, and in tanning leather and dyeing textiles. Potassium is essential to life, and non-toxic. One of its natural isotopes is radioactive, and although this radioactivity is mild, it may be one natural cause of genetic mutation in man.

Symbol: K
Atomic number: 19
Atomic weight: 39.0983
Density (at room temperature and pressure): 0.862 g/cc
Melting point: 63.38°C
Boiling point: 760°C
Main valence: +1
Ground state electron configuration: [Ar]4s1

Po*tas"si*um (?), n. [NL. See Potassa, Potash.] Chem.

An Alkali element, occurring abundantly but always combined, as in the chloride, sulphate, carbonate, or silicate, in the minerals sylvite, kainite, orthoclase, muscovite, etc. Atomic weight 39.0. Symbol K (Kalium).

⇒ It is reduced from the carbonate as a soft white metal, lighter than water, which oxidizes with the greatest readiness, and, to be preserved, must be kept under liquid hydrocarbons, as naphtha or kerosene. Its compounds are very important, being used in glass making, soap making, in fertilizers, and in many drugs and chemicals.

Potassium permanganate, the salt KMnO4, crystallizing in dark red prisms having a greenish surface color, and dissolving in water with a beautiful purple red color; -- used as an oxidizer and disinfectant. The name chameleon mineral is applied to this salt and also to potassium manganate. -- Potassium bitartrate. See Cream of tartar, under Cream.


© Webster 1913.

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