|a compound of high molecular weight derived either by the addition of many smaller molecules, as polyethylene, or by the condensation of many smaller molecules with the elimination of water, alcohol, or the like, as nylon.|
|any of a group of carbohydrates, as sucrose or lactose, that yield monosaccharides on hydrolysis.|
|a. a colourless odourless highly reactive gaseous element: the most abundant element in the earth's crust (49.2 per cent). It is essential for aerobic respiration and almost all combustion and is widely used in industry. Symbol: O; atomic no: 8; atomic wt: 15.9994; valency: 2; density: 1.429 kg/m³; melting pt: --218.79°C; boiling pt: --182.97°C|
|b. (as modifier): an oxygen mask|
oxygen ox·y·gen (ŏk'sĭ-jən)
An element constituting 21 percent of the atmosphere by volume that occurs as a diatomic gas, O2, combines with most elements, is essential for plant and animal respiration, and is required for nearly all combustion. Atomic number 8; atomic weight 15.9994; melting point -218.8°C; boiling point -183.0°C; gas density at 0°C 1.429 grams per liter; valence 2.
A medicinal gas containing not less than 99.0 percent, by volume, of O2.
|oxygen (ŏk'sĭ-jən) Pronunciation Key
A nonmetallic element that exists in its free form as a colorless, odorless gas and makes up about 21 percent of the Earth's atmosphere. It is the most abundant element in the Earth's crust and occurs in many compounds, including water, carbon dioxide, and iron ore. Oxygen combines with most elements, is required for combustion, and is essential for life in most organisms. Atomic number 8; atomic weight 15.9994; melting point -218.4°C; boiling point -183.0°C; gas density at 0°C 1.429 grams per liter; valence 2. See Periodic Table.
Our Living Language : In 1786, the French chemist Antoine Lavoisier coined a term for the element oxygen (oxygène in French). He used Greek words for the coinage: oxy- means "sharp," and -gen means "producing." Oxygen was called the "sharp-producing" element because it was thought to be essential for making acids. Lavoisier also coined the name of the element hydrogen, the "water-producing" element, in 1788. Soon after, in 1791, another French chemist, J. A. Chaptal, introduced the word nitrogen, the "niter-producing" element, referring to its discovery from an analysis of nitric acid.
Note: When we breathe in oxygen, it is carried by the hemoglobin in our blood throughout the body, where it is used to generate energy by oxidation. (See respiration.)
Note: Oxygen is a waste product of green plants and photosynthesis.