atomic number

atomic number   n.   Symbol Z Abbr. at. no. The number of protons in an atomic nucleus.

atomic number

The number of protons or electrons normally found in an atom of a given chemical element. The higher the atomic number, the heavier the atom is. In a neutral atom, the number of protons and electrons is the same. (See atomic weight and periodic table of the elements.)

Main Entry: atomic num·ber
Pronunciation: -'n&m-b&r
Function: noun
: an experimentally determined number characteristic of a chemical elementthat represents the number of protons in the nucleus which in a neutral atom equals the number of electrons outside the nucleus and that determines the place of the element in the periodic table—see ELEMENT table

atomic number n.
Abbr. at. no., at no
The number of protons in an atomic nucleus; it indicates the position of an element in the periodic table.