Question

the \atomic number\ of an atom is determined by the number of ________ it has. a b electrons c neutrons d protons e protons + electrons

Explanation:

The atomic number of an atom is defined as the number of protons in its nucleus. Electrons can be lost or gained (in ions), neutrons vary in isotopes, and protons + electrons is not a standard definition for atomic number.

Answer:

D. protons