Symbol: K
Atomic number: 19
Atomic mass: 39.0983
Group: Alkali Metal
CAS-number: 7440-09-7

Physical data
Other info
Kr Krypton To Periodic Table CalciumCa

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Physical data

Electronic data

Shells: 2, 8, 8, 1
Orbitals: [Ar] 4s1
Electronegativity: 0.8, 0.9
1. Ionization potential: 4.3407 eV
2. Ionization potential: 31.625 eV
3. Ionization potential: 45.72 eV
Oxidation states: 1
Electrical conductivity: 0.139 10^6

Thermal data

Melting point: 63.25 °C
Boiling point: 759.9 °C
Specific heat: 0.75 J/gK
Heat of fusion: 2.334 kJ/mol
Heat of vaporization: 79.870 kJ/mol
Thermal conductivity: 1.024 W/cmK

Steric data

Atomic radius: 2.77 Å
Ionic radius: 1.51 Å (+1)
Covalent radius: 2.03 Å
Atomic volume: 45.46 cm³/mol
Density (293 K): 0.862 g/cm³
Crystal structure: cubic body centered
cubic body centered


NuclideAbundance [%]MassSpinHalflifeDecay modeDecay tree
39K 93.22 38.9637 3/2 -- --
40K 0.118 39.974 4 1.28E09y β-, β+ View
41K 6.77 40.9618 3/2 -- --
42K 0 41.963 2 12.36h β- View
43K 0 43 3/2 22.3h β- View

Other info

Name origin:English: pot ash; symbol from Latin: kalium, (alkali)
Description:Soft, waxy, silver-white metal. Eighth most abundant element in the earth's crust (20,900 ppm). Occurs only in compounds.
Discovered by:Sir Humphrey Davy
Sources:Found in minerals like carnallite [(KMgCl3).6H2O] and sylvite (potassium chloride, KCl). Pure metal is produced by the reaction of hot potassium chloride and sodium vapors in a special retort.
Use(s):Used as potash in making glass & soap. Also as saltpeter, potassium nitrate (KNO3) to make explosives and to color fireworks in mauve. Formerly called kalium (K). Vital to function of nerve and muscle tissures.