what determines an atom's identity?

Question

number of electrons
valence number
number of neutrons
number of protons

Answer 1

The number of protons determines an atom's identity. This is because the number of protons in an atom's nucleus defines its atomic number, which is unique to each element. For example, an atom with 6 protons is carbon, while an atom with 79 protons is gold. The number of electrons, neutrons, and valence number can vary for different isotopes or ions of the same element, but the number of protons remains constant and defines the atom's identity.