Relative atomic mass: 39.0983 +- 0.0001

English: Potassium
French: Potassium
Croatian: Kalij
German: Kalium
Italian: Potassio
Spanish: Potasio

Atomic number: 19
Group numbers: 1
Period: 4
Standard state (20 oC): solid

Discovery: 1807 Sir Humphry Davy (GB)
Potassium was discovered by Sir Humphry Davy (GB) in 1807. The origin of the name comes from the Arabic word qali meaning alkali (the origin of the symbol K comes from the Latin word kalium). It is a soft, waxy, silver-white metal. Fresh surfaces have a silvery sheen. Potassium quickly forms dull oxide coating on exposure to air. It reacts strongly with water and gives off a flammable gas. It also reacts violently with oxidants. Potasium occurs only in compounds. Potassium is found in minerals like carnallite [(KMgCl3).6H2O] and sylvite (KCl). Pure metal is produced by the reaction of hot potassium chloride and sodium vapours in a special retort. Pottasium is used as potash in making glass and soap and as saltpetre, potassium nitrate (KNO3) to make explosives and to colour fireworks in mauve. Potassium ions are vital to function of nerve and muscle tissues. The price of 90.2 % pure potassium metal is 90.20 for 5 g.
Electronic configuration: [Ar] 4s1
Formal oxidation number: +1
Atomic radius: 227.2 pm

Electronegativities: 0.82
Thermal conductivity: 102 W/(m K)
Electrical resistivity (20 oC): 6.15 microOhm cm

Melting point: 63.28 oC
Boiling point: 759 oC

Heat of fusion: 2.4 kJ/mol
Heat of vaporization: 79.1 kJ/mol
Heat of atomization: 90.14 kJ/mol

18Ar <= 19K => 20Ca

ASCII Periodic Table of the Elements
29 Aug. 2017
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