Oxygen is the element with atomic number 8 and symbol O. It exists in nature as a diatomic molecule and is a gas at room temperature. Oxygen is the second most abundant gas in Earth's atmosphere and is required for the survival of most living organisms. Highly reactive, oxygen is consumed in all combustion reactions and its presence leads to oxidation of other materials. Oxygen was discovered independently in 1772 by Carl Wilhelm Scheele and 1774 by Joseph Priestly. The gas was later named oxygen by Antoine Lavoisier.

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