[W/K] :: sodium

  Sodium \So"di*um\, n. [NL., fr.E. soda.] (Chem.)
     A common metallic element of the alkali group, in nature
     always occuring combined, as in common salt, in albite, etc.
     It is isolated as a soft, waxy, white, unstable metal, so
     highly reactive that it combines violently with water, and to
     be preserved must be kept under petroleum or some similar
     liquid. Sodium is used combined in many salts, in the free
     state as a reducer, and as a means of obtaining other metals
     (as magnesium and aluminium) is an important commercial
     product. Symbol Na ({Natrium). Atomic weight 22.990.
     Specific gravity 0.97.
     [1913 Webster]
  
     Sodium amalgam, an alloy of sodium and mercury, usually
        produced as a gray metallic crystalline substance, which
        is used as a reducing agent, and otherwise.
  
     Sodium carbonate, a white crystalline substance,
        Na2CO3.10H2O, having a cooling alkaline taste, found in
        the ashes of many plants, and produced artifically in
        large quantities from common salt. It is used in making
        soap, glass, paper, etc., and as alkaline agent in many
        chemical industries. Called also sal soda, washing
        soda, or soda. Cf. Sodium bicarbonate, and Trona.
        
  
     Sodium chloride, common, or table, salt, NaCl.
  
     Sodium hydroxide, a white opaque brittle solid, NaOH,
        having a fibrous structure, produced by the action of
        quicklime, or of calcium hydrate (milk of lime), on sodium
        carbonate. It is a strong alkali, and is used in the
        manufacture of soap, in making wood pulp for paper, etc.
        Called also sodium hydrate, and caustic soda. By
        extension, a solution of sodium hydroxide.
        [1913 Webster]

  Natrium \Na"tri*um\, n. [NL. See Natron.] (Chem.)
     The technical name for sodium.
     [1913 Webster]

  sodium
       n : a silvery soft waxy metallic element of the alkali metal
           group; occurs abundantly in natural compounds (especially
           in salt water); burns with a yellow flame and reacts
           violently in water; occurs in sea water and in the
           mineral halite (rock salt) [syn: Na, atomic number 11]

  sodium
  Symbol: Na
  Atomic number: 11
  Atomic weight: 22.9898
  Soft silvery reactive element belonging to group 1 of the periodic table
  (alkali metals). It is highly reactive, oxidizing in air and reacting
  violently with water, forcing it to be kept under oil. It was first
  isolated by Humphrey Davy in 1807.