atomic number
2 synonyms for atomic number, grouped by meaning and by how common each one is.
Noun — The number of protons in the nucleus of an atom, which determines what element the atom is and where it sits on the periodic table.
Synonyms
Rare, literary or technical
Precise, but they will stand out — check the sense before using one.
proton number
Z
How to use atomic number
The word patterns that sound natural to a native speaker.
increasing atomic number
atomic number 26
proton number
in order of atomic number
Chemistry and physics. It is written as a subscript before the element symbol and often labelled Z.
Frequently asked questions
What does the atomic number tell you?
It tells you how many protons are in the nucleus, and therefore which element you are dealing with. In a neutral atom it also gives the number of electrons, which sets the element's chemical behaviour.
Why are elements ordered by atomic number rather than atomic mass?
Ordering by mass puts a few pairs, such as argon and potassium, in the wrong chemical groups. Sorting by proton count fixes those anomalies because it reflects the underlying structure that actually governs how elements react.
