Classification of Matter

Terms and definitions

Atom

An atom is the smallest particle of an element

Element

An element is the purest form of a matter, each element consist of different numbers of protons.

Molecule

Molecules are matter composed of two or more atoms, it usually have unique properties distinct from the atoms it's composed of.

Note that I said molecules are composed of more than one atoms, not elements, which brings us to:

Compound

Compounds are molecules comprised of more than one elements