Text: Three states of matter

Matter may exist as a solid, a liquid or a gas. The same substance, such as water, may exist in any of these forms. Water is a liquid but if it is cold enough it can become a solid, ice, and if it is hot enough it can become steam, or gaseous water.

The reason for the difference in these states of matter is heat. Heat is not matter. It is a form of energy of the molecules and atoms of matter.

As already stated, matter may exist in three states: 1) the solid state, 2) the liquid state, 3) the gaseous state. If a solid is heated sufficiently, it can be made to melt, liquefy or vaporize. As a vapour, it is in the gaseous state. If, on the other hand, a gas is cooled sufficiently, it will condense and become a liquid. The continued cooling of a liquid will cause it to solidify or freeze. In the case of water, nature performs all these changes of state: ice is melted to become water, and water is vaporized to become steam; water vapour or clouds condense to become rain, and rain freezes to become ice. Although it may sometimes require extreme heat or extreme cold, all substances can be transformed from any one state to another.