An atom is made up of protons, neutrons, and electrons.
When an atom is charged, it becomes an ion.
Dalton believed that the molecules of the elementary gases consisted each of one atom; his diagram for hydrogen gas makes the point clear.
There's not an atom of dirt in her house because she never stops cleaning.
The breaking down of atoms is what provides nuclear energy.
It was against them that was broken his invincible will, sweeping away in the defeat the work of Panama, his own fortune, his fame and almost an atom of his honour.
Some elements only exist in nature in pairs of atoms, including hydrogen, nitrogen, and iodine.
A molecule may be defined as the smallest part of a substance which can exist alone; an atom as the smallest part of a substance which can exist in combination.
I couldn't find an atom of hatred in the sweet, innocent girl.
What atom is most prevalent in Earth's atmosphere?