English

Definition of atomic number noun from the Oxford Advanced Learner's Dictionary

 

atomic number

 noun
noun
BrE
 
; NAmE
 
(chemistry) Molecules and matter
 
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the number of protons in the nucleus (= centre) of an atom, which is characteristic of a chemical element. Elements are placed in the periodic table according to their atomic numbers. See related entries: Molecules and matter
See the Oxford Advanced American Dictionary entry: atomic number