Oxygen
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Oxygen | |
---|---|
Properties | |
Atomic symbol | O |
Atomic number | 8 |
Classification | Non-metal |
Atomic mass | 15.994 amu |
Other Information | |
Date of discovery | 1774 |
Name of discoverer | Joseph Priestley |
Name origin | From the Greek words oxus (acid) and gennan (generate) |
Uses | Supports life |
Obtained from | From liquid air |
Oxygen is the third most abundant element in the universe by mass and is essential to life on Earth.
Chemical Properties
At normal atmospheric pressure oxygen melts at 54.36 Kelvin (K) and boils at 90.2 K; on Earth it essentially exists only as a gas. It readily dissolves in water, which makes aquatic life possible. Under normal conditions oxygen forms molecules consisting of two oxygen atoms each sharing two electrons in the 2p subshell; this form of oxygen is known as O2. O2 is a pale blue odourless gas.