ox·y·gen /ˈɑksɪʤən/ 名詞
氧 O *
1. Chem. A colorless, tasteless, odorless, gaseous element of atomic number 8, 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 15.9994.
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]
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]
Atomic number: 8
Atomic weight: 15.9994
A colourless, odourless gaseous element belonging to group 16 of the
periodic table. It is the most abundant element present in the earth's
crust. It also makes up 20.8% of the Earth's atmosphere. For industrial
purposes, it is separated from liquid air by fractional distillation. It
is used in high temperature welding, and in breathing. It commonly comes
in the form of Oxygen, but is found as Ozone in the upper atmosphere. It
was discovered by Priestley in 1774.