Potassium - Periodic Table of the Elements

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PERIODIC TABLE OF THE ELEMENTS version 1.7


 K

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


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

Potassium was discovered by Sir Humphry Davy (England) 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 soft, waxy, silver-white metal. Fresh surface has silvery sheen. Quickly forms dull oxide coating on exposure to air. Reacts strongly with water. Reacts with water to give off flammable gas. Reacts violently with oxidants. Occurs only in compounds.

Electronic configuration: [Ar] 4s¹
Relative atomic mass: 39.0983(1)
Formal oxidation number: +1

Electronegativities: 0.82
Thermal conductivity: 102 W/(m K)
Electrical resistivity (20 °C): 6.15 μΩcm

Atomic radius: 227.2 pm
Density (g/dm3): 862 (293 K) 
828 (m.p.)
Molar volume (cm3/mol): 45.36 (293 K) 
47.22 (m.p.)

Melting point: 63.38 °C
Boiling point: 759 °C
Critical temperature: 1950 °C

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

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. Used as potash in making glass and soap. Also as saltpetre, potassium nitrate (KNO3) to make explosives and to colour fireworks in mauve. Vital to function of nerve and muscle tissues. The price of 90.2 % pure potassium metal is 90.20 € for 5 g. 18Ar <= 19K => 20Ca ___________________ If you have comments, corrections or suggestions about this site, please send me a e-mail. Periodic Table of the Elements __________________________________ Last modified: 29.03.2003 Copyright © 1998-2003 by Eni Generalic