資料來源 : pyDict

U氧,氧氣

資料來源 : Webster's Revised Unabridged Dictionary (1913)

Oxygen \Ox"y*gen\, n. [F. oxyg[`e]ne, from Gr. ???? sharp, acid
   + root of ???? to be born. So called because originally
   supposed to be an essential part of every acid.]
   1. (Chem.) A colorless, tasteless, odorless, gaseous element
      occurring in the free state in the atmosphere, of which it
      forms about 23 per cent by weight and about 21 per cent by
      volume, being slightly heavier than nitrogen. Symbol O.
      Atomic weight 15.96.

   Note: It occurs combined in immense quantities, forming eight
         ninths by weight of water, and probably one half by
         weight of the entire solid crust of the globe, being an
         ingredient of silica, the silicates, sulphates,
         carbonates, nitrates, etc. Oxygen combines with all
         elements (except fluorine), forming oxides, bases,
         oxyacid anhydrides, etc., the process in general being
         called oxidation, of which combustion is only an
         intense modification. At ordinary temperatures with
         most substances it is moderately active, but at higher
         temperatures it is one of the most violent and powerful
         chemical agents known. It is indispensable in
         respiration, and in general is the most universally
         active and efficient element. It may be prepared in the
         pure state by heating potassium chlorate. This element
         (called dephlogisticated air by Priestley) was named
         oxygen by Lavoisier because he supposed it to be a
         constituent of all acids. This is not so in the case of
         a very few acids (as hydrochloric, hydrobromic, hydric
         sulphide, etc.), but these do contain elements
         analogous to oxygen in property and action. Moreover,
         the fact that most elements approach the nearer to acid
         qualities in proportion as they are combined with more
         oxygen, shows the great accuracy and breadth of
         Lavoisier's conception of its nature.

   2. Chlorine used in bleaching. [Manufacturing name]

資料來源 : WordNet®

oxygen
     n : a nonmetallic bivalent element that is normally a colorless
         odorless tasteless nonflammable diatomic gas; constitutes
         21 percent of the atmosphere by volume; the most abundant
         element in the earth's crust [syn: {O}, {atomic number 8}]