Outline of water
The following outline is provided as an overview of and topical guide to water: Water is a chemical substance with the chemical formula HO. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state (water vapor or steam). Under nomenclature used to name chemical compounds, "Dihydrogen monoxide" is the scientific name for water, though it is almost never used.