* Potassium is a member of the alkali metals family:
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POTASSIUM / K / 19
A soft, silvery-white, highly reactive metal. The symbol "K" comes
from the Latin "kalium", meaning "potash". Three isotopes are
found in nature:
K<39/19> / 93%
K<41/19> / 7%
K<40/19> / 0.012%
The first two isotopes are stable, but K<40/19> is unstable, with a
half-life of 1.3E9 years.
atomic weight: 39.0938
abundance: 8th
density: 0.862 gm/cc
melting point: 63 C
boiling point: 760 C
valence: 1
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Potassium is heavily produced, in tens of millions of tonnes per year, mostly for fertilizer. Potassium compounds have other uses as well. Potassium carbonate (K2CO3) or potash is used in the manufacture of specialized glasses; potassium chlorate (KClO3) is used in the manufacture of match-heads and some components of fireworks; and potassium nitrate or "saltpeter" (KNO3) is used as a major component of "black powder" for fireworks.
Potassium itself is an important nutrient, but potassium chloride (KCl) has the notoriety of being used in executions by lethal injection. It causes a massive electrolyte imbalance that stops the heart, but is otherwise so benign that the victim may be used as an organ donor.
