Molecular formula : H₂ O. One oxygen is covalently (single) bonded to two hydrogen atoms.
Water in solid form: ICE
Ice is a transparent, crystalline solid. It is colorless and odorless. Ice is a hard substance. Its density is less than that of water. So ice floats in water. Volume of ice is more than volume of water liquid. Melting point of ice is decreased with addition of salt.
Ice is slippery because on the surface ice melts when high pressure (stress) is applied. Ice can work as a converging or diverging lens.
Water (liquid form) : water
Water becomes liquid from Ice at 0° C at normal atmospheric pressure. Water takes a latent heat of 4.18 Joules/gm to become water at 0°C. Pure water is not a good conductor of electricity. It has a high specific heat capacity.
It is colorless, transparent to light, odorless and tasteless.
It is neutral in terms of acidity or alkalinity. It is a solvent for many chemical compounds.
Water is formed when Hydrogen and oxygen react at a high temperature.
Water in gaseous form : water vapor
Water boils at 100°C at atmospheric pressure.
Water molecules take a latent heat of Joules/gm to become vapour from liquid. Vapor is color less and odorless. Water vapor is used to convert heat energy into mechanical energy (steam engines) and into electrical energy (AC generator). Water vapor is present in air in the atmosphere and is called humidity. Higher humidity is uncomfortable for people.