Definition of atomic number in English:

atomic number

Syllabification: a·tom·ic num·ber

noun

Chemistry & Physics
  • The number of protons in the nucleus of an atom, which determines the chemical properties of an element and its place in the periodic table. (Symbol: Z)
    More example sentences
    • In those cases in which the number of protons changes, the new nucleus has a different atomic number, and it therefore belongs to a different element.
    • In a neutral atom, the number of electrons is equal to the number of protons, therefore, the atomic number also indicates the number of electrons in an atom.
    • We now have data on the properties of 29 new nuclei with atomic numbers between 104 and 118.

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