oxygen

[ ok-si-juhn ]

noun

, Chemistry.

1. a colorless, odorless, gaseous element constituting about one-fifth of the volume of the atmosphere and present in a combined state in nature. It is the supporter of combustion in air and was the standard of atomic, combining, and molecular weights until 1961, when carbon 12 became the new standard. : O; : 15.9994; : 8; density: 1.4290 grams/liter at 0°C and 760 millimeter pressure.

oxygen

/ ˈɒksɪdʒən; ɒkˈsɪdʒɪnəs; ˌɒksɪˈdʒɛnɪk /

noun

1. 1. 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
   2. ( as modifier )

      an oxygen mask

oxygen

/ ŏk′sĭ-jən /

1. 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 −218.8°C; boiling point −182.9°C; gas density at 0°C 1.429 grams per liter; valence 2.
2. See Periodic Table

oxygen

1. An element , normally a gas , that makes up about one-fifth of the atmosphere of the Earth . Oxygen is usually found as a molecule made up of two atoms . Its symbol is O.

Notes

Oxygen is a waste product of green plants and photosynthesis .

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 .)

Derived Forms

• oxygenic, adjective

Other Words From

• ox·y·gen·ic [ok-si-, jen, -ik], ox·yg·e·nous [ok-, sij, -, uh, -n, uh, s], adjective
• ox·y·gen·ic·i·ty [ok-si-j, uh, -, nis, -i-tee], noun

Word History and Origins

Origin of oxygen¹

First recorded in 1780–90; from French oxygène, equivalent to oxy- + -gène; oxy- ¹, -gen

Word History

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.

Example Sentences

The others are difficult to identify, since they reacted with other oxygen-bearing molecules in the soil.

From The Daily Beast

It reacts very readily with oxygen by burning smokelessly, with carbon dioxide and water as its byproducts.

From The Daily Beast

Their decay proceeded without a ready supply of oxygen, producing hydrocarbons like methane instead of oxygen-bearing molecules.

From The Daily Beast

As the heart pumps blood to the far reaches of the body, it requires its own blood flow to receive vital oxygen and nutrients.

From The Daily Beast

The brain, also an organ, is particularly sensitive to the loss of oxygen.

From The Daily Beast

In the lungs hemoglobin forms a loose combination with oxygen, which it readily gives up when it reaches the tissues.

From Project Gutenberg

They are cells which have been highly differentiated for the purpose of carrying oxygen from the lungs to the tissues.

From Project Gutenberg

Its most important compound is water, of which it forms one-ninth, the other eight-ninths consisting of oxygen.

From Project Gutenberg

In the flowers, both by day and night, there is a constant absorption of oxygen, and evolution of carbonic acid.

From Project Gutenberg

In the first case, the oil rapidly combines with the oxygen of the air, this being accompanied by great heat.

From Project Gutenberg