Question

composition of atoms quick check
what determines an atom’s identity? (1 point)
the number of neutrons
the number of protons
the number of electrons
the valence number

Explanation:

The atomic number, which is determined by the number of protons in the nucleus of an atom, defines what element the atom is. Different elements have unique numbers of protons. Neutrons affect the isotope of an atom, electrons are involved in chemical bonding and can change in number in ions, and valence number relates to an atom's reactivity and bonding capacity, not its identity as an element.

Answer:

the number of protons