# What is an atom, element, molecule, and compound? What is an example of each?

Mar 29, 2017

Atom is a particle of matter that characterizes a chemical element.

#### Explanation:

An atom is a particle of matter that characterizes a chemical element. It is the smallest part of ordinary matter. It is made from particles called protons, neutrons and electrons called the subatomic particles.

An element is a substance that is made entirely of one type of atom. For example, the element sodium is made up of only sodium atoms.

A molecule is a substance that contains two or more atoms chemically joined, such as ${H}_{2} , {O}_{2}$

A compound is a substance that is made up of two or more different elements that are chemically joined, such as ${H}_{2} O , C O , N a C l$.

Note: All compounds are molecules, but not all molecules are compounds.