What is the difference between an atom and a molecule?

An atom is one basic unit. A molecule is two or more atoms joined together.

Is atom a common word in academic writing?

Yes. It is very common in science, chemistry, and physics.

Can atom be used outside science?

Yes. It can mean a very tiny amount, often in phrases like “an atom of truth.”

Is atom formal or informal?

It is a neutral scientific word, common in both study and teaching.

← Dictionary

atom

/ˈæt.əm/

IELTSAcademic

noun

the smallest unit of a chemical element that still has the properties of that element. An atom has a nucleus and electrons.

Water is made of atoms.
Carbon is an atom in many living things.
The atom is too small to see directly.

Adinary Nuance

Atom is the basic scientific word for a tiny part of matter. It is more precise than “particle,” which can mean many different small things. It is also different from “molecule,” which is made of two or more atoms joined together. In science writing, choose atom when you mean one element's smallest unit.

In other languages

Vietnamese: nguyên tử
Spanish: átomo
Chinese: 原子
Japanese: 原子
Korean: 원자

Etymology

Atom comes from Greek atomos, meaning “indivisible” or “uncuttable.” The word entered English through Latin and French, and later became a key term in science.

Common phrases

an atom of truthsplit the atomatom bombthe structure of the atom

Synonyms

particle unit

Frequently asked questions

What is the difference between an atom and a molecule?: An atom is one basic unit. A molecule is two or more atoms joined together.
Is atom a common word in academic writing?: Yes. It is very common in science, chemistry, and physics.
Can atom be used outside science?: Yes. It can mean a very tiny amount, often in phrases like “an atom of truth.”
Is atom formal or informal?: It is a neutral scientific word, common in both study and teaching.