What distinguishes the atom of one element from the atom of a different element

What distinguishes the atom of one element from the atom of a different element?


A. the number of protons in the atom
B. the number of neutrons in the atom
C. the number of electrons in the atom
D. the number of electron orbitals in the atom

A. The number of protons in the atom.

@arshadali- You really shouldn't go around spreading false information. Isotopes are elements with different masses because they have a different number of neutrons, not protons. Also, the number of electrons compared to the number of protons for an atom determines the ionization of the atom, not the element itself.

c.as number of protons can be different in atoms of same elements..like in isotopes

a