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potassium [K, kalium]
From the English potash. The symbol K comes from the Latin kalium meaning alkali. Isolated in 1807 by Sir Humphrey Davy.
Occurrence:
1) 7th most abundant metal
2) occurs abundantly in nature esp combined in minerals
3) never found free in nature
4) found in most soils
Characteristics:
1) silver-white soft light low-melting univalent metallic element of the alkali metal group
2) 2nd least dense metal (after lithium)
3) oxidizes very rapidly in air
4) must be stored under argon or mineral oil
5) potassium & its salts impart a lilac color to flames
6) reacts with water
K + H2O -> K+ + OH- + H2 + heat
the heat generally ignites the H2 (in the presence of O2)
Uses:
1) metal rarely used
2) salts of K+ used in
a) fertilizers
b) match heads
c) glass
d) soaps
e) detergents
3) K-40 isotope is used to date rocks
Related
K+
periodic table
General
alkali metal
Properties
SIZE: AW = 22.99
atomic number
VALUE: 19
VALENCE: AR 4S1
Database Correlations
PUBCHEM correlations
References
- Webster's Ninth New Collegiate Dictionary, Miriam-
Webster Inc. Springfield, MA 1990
- Chemical & Engineering News, Sept 8, 2003
Component-of
phosphorus/potassium