the number of protons in the nucleus of an atom of an element
Abbreviation: at. no.. Symbol: Z. Also called: proton number
atomic number in American English
Chemistry
a number representing the relative position of an element in the periodic table, in which the elements are arranged in the order of their nuclear charges; a number representing the positive charge or the number of protons in the nucleus of the atom of an element: isotopes have the same atomic number but different mass numbers
Examples of 'atomic number' in a sentence
atomic number
Yes, it's a radioactive substance with an atomic number higher than uranium - that makes it potentially deadly to humans.