What subatomic particle, found in the nucleus of an atom, is solely responsible for determining the element’s atomic number and, consequently, its chemical identity?

💡 Explanation:

The atomic number (Z) of an element is defined by the number of protons in the nucleus. Changes in the number of neutrons result in isotopes (variants of the same element), and changes in the number of electrons result in ions (charged atoms), but only changing the number of protons changes the element itself.