POTASSIUM (K)

last update 01 oct 08

* 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 g/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.