How are atoms and molecules different?

Question

Wyatt Adkins · Accepted Answer

The main difference relies on the fact that molecules are sets of atoms.

A molecule is a union of atoms. Atoms are made up of an electron shell and a nucleus, which includes protons and neutrons. Chemical bonds are created by interactions between electrons from different atoms (such as exchanges or sharing). While there are smaller entities than atoms (such as particles or quarks), they do not represent any kind of element (in the same way that screws and gears are not real engines, but rather a part of them). Nevertheless, not all atomic unions are referred to as molecules. For example, in metals, atoms are joined to one another, but they form a lattice rather than a molecule. Molecular compounds are composed exclusively by molecules. For instance, water is composed by #"H"_2 "O"# molecules. 200 molecules of #"H"_2 "O"# are water; 400 atoms of H and 200 atoms of O, without any bond between them, are not water. Nevertheless, 200 atoms of Fe are iron, and 10 atoms do too. Moreover, molecules interact with one another through forces known as Van der Waals forces.

Serenity Allen · Answer

undefined Atoms are the basic units of matter, while molecules are formed when two or more atoms chemically combine.