Editing Molecule (section)

== Prevalence ==
{{Unreferenced section|date=August 2022}}
Molecules as components of matter are common. They also make up most of the oceans and atmosphere. Most organic substances are molecules. The substances of life are molecules, e.g. proteins, the amino acids of which they are composed, the nucleic acids (DNA and RNA), sugars, carbohydrates, fats, and vitamins. The nutrient minerals are generally ionic compounds, thus they are not molecules, e.g. iron sulfate.

However, the majority of familiar solid substances on Earth are made partly or completely of crystals or ionic compounds, which are not made of molecules. These include all of the minerals that make up the substance of the Earth, sand, clay, pebbles, rocks, boulders, [[Crust (geology)|bedrock]], the [[Mantle (geology)|molten interior]], and the [[Earth core|core of the Earth]]. All of these contain many chemical bonds, but are ''not'' made of identifiable molecules.

No typical molecule can be defined for salts nor for [[network solid|covalent crystals]], although these are often composed of repeating [[unit cell]]s that extend either in a [[Plane (mathematics)|plane]], e.g. [[graphene]]; or three-dimensionally e.g. [[diamond]], [[quartz]], [[sodium chloride]]. The theme of repeated unit-cellular-structure also holds for most metals which are condensed phases with [[metallic bond]]ing. Thus solid metals are not made of molecules. In [[glass]]es, which are solids that exist in a vitreous disordered state, the atoms are held together by chemical bonds with no presence of any definable molecule, nor any of the regularity of repeating unit-cellular-structure that characterizes salts, covalent crystals, and metals.