General | States | Energies | Oxidation & Electrons |Appearance & Characteristics
Reactions | Other Forms |Radius | Conductivity | Abundance
Encyclopedia Britannica articles


Name Potassium Symbol K
atomic number 19 Atomic weight 39.0983
Density @ 293 K 0.862 g/cm3 Atomic volume 45.46 cm3/mol
Group Alkali Met. discovered 1807


state (s, l, g) s
melting point 336.5 K boiling point 1038.7 K
Heat of fusion 2.334 kJ/mol Heat of vaporization 79.870 kJ/mol
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1st ionization energy 418.8 kJ/mole electronegativity 0.82
2nd ionization energy 3051.3 kJ/mole electron affinity 48.385 kJ/mole
3rd ionization energy 4411.3 kJ/mole Specific heat 0.75 J/gK
heat atomization 90 kJ/mole atoms

Oxidation & Electrons

Shells 2,8,8,1 electron configuration [Ar] 4s1
minimum oxidation number 0 maximum oxidation number 1
min. common oxidation no. 0 max. common oxidation no. 1
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Appearance & Characteristics

structure bcc: body-centered cubic color silvery-white
uses fertilizer, low-Na salt toxicity
hardness 0.5 mohs characteristics soft


reaction with air vigorous, = KO2 reaction with 6M HCl vigorous, = H2, KCl
reaction with 6M HCl vigorous, = H2, KCl reaction with 15M HNO3 vigorous, = H2, NOx, KNO3
reaction with 6M NaOH vigorous, = H2, KOH
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Other Forms

number of isotopes 3 hydride(s) KH
oxide(s) K2O chloride(s) KCl


ionic radius (2- ion) pm ionic radius (1- ion) pm
atomic radius 227 pm ionic radius (1+ ion) 152 pm
ionic radius (2+ ion) pm ionic radius (3+ ion) pm
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thermal conductivity 102.5 J/m-sec-deg electrical conductivity 138.9 1/mohm-cm
polarizability 43.4 A^3


source Sylvite, carnallite (misc) rel. abund. solar system 3.576 log
abundance earth's crust 4.3 log cost, pure 85 $/100g
cost, bulk $/100g
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World Wide Web presentation of Chemicool Periodic Table is © Copyright 1996-99 by David D. Hsu. Some data were provided by and used with the permission of JCE Software and is owned and copyright by the Division of Chemical Education, Inc. Additional data were provided by Perkin-Elmer through Peter Lykos of IIT. The information may not be redistributed without the permission of David Hsu or JCE Software.