The atomic number of an element represents the number of protons in the nucleus of each atom of that element. This number uniquely identifies the element because every atom of a given element has the same number of protons

. Additionally, in a neutral atom, the atomic number also equals the number of electrons, since the positive charge of the protons is balanced by the negative charge of the electrons

. Thus, the atomic number is fundamental for classifying elements and determining their position in the periodic table, as elements are arranged in order of increasing atomic number