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Science · Grades 3–4

Atom

noun

The smallest particle of a chemical element that can exist.

Example Sentences

"All matter is made of atoms."

"An atom is so tiny that millions would fit on the period at the end of this sentence."

Synonyms & Related Terms

particleelement unit

Quick Check

Which best describes the meaning of atom?

Study Tips

To remember atom, try writing it in a sentence of your own. Connect it to something you already know about science.

Use it in conversation today — saying a word aloud three times helps lock it into long-term memory.