At lowly levels these beings are elementary entities, known as Elementals.

The number of elementary entities in a sample of a substance is technically called its (chemical) amount.

In a country which includes some 13,000 villages, the village is considered, by a 1972 decree, the elementary entity in the administrative body of the nation.

The mole may also be used to express the number of atoms, ions, or other elementary entities in a given sample of any substance.

The amount of substance is proportional to the number of specified elementary entities of that substance.

Amount of substance is a standards-defined quantity that measures the size of an ensemble of elementary entities, such as atoms, molecules, electrons, and other particles.

The mole is the amount of substance of a system which contains as many elementary entities as there are carbon atoms in 0.012 kilogram of carbon-12.

The elementary entities must be specified and may be atoms, molecules, ions, electrons, other particles, or specified groups of such particles.

The International System of Units (SI) defines the amount of substance to be equal to the number of elementary entities present.

The mole is defined as the amount of substance that has an equal number of elementary entities as there are atoms in 12 gram of carbon-12 .

The identity of "elementary entities" depends on the context and it must be stated; usually these entities are one of the following: atoms, molecules, ions, or Elementary particle such as electrons.

It is defined as the amount of any chemical substance that contains as many elementary entities, e.g., atoms, molecules, ions, electrons, or photons, as there are atoms in 12 grams of pure carbon-12 (C), the isotope of carbon with relative atomic mass 12 by definition.