atomic number

From Wiktionary

[change] Pronunciation

• IPA: /əˈtɒm.ɪk//ˈnʌm.bɚ/

[change] Noun

Singular atomic number

Plural atomic numbers

1. (countable) The number of protons in an atom is the atomic number. It is also the position in the periodic table of elements.

   Hydrogen has an atomic number of 1. It has 1 proton, and is the first element in the periodic table.

   Heavy elements, such as gold have a high atomic number.