What do an orgasm, a multiplication problem and a photo of a dead body have in common? Each induces a slight, irrepressible expansion of the pupils in our eyes, giving careful observers a subtle but meaningful signal that thoughts and feelings are afoot. For more than a century, scientists have known that our pupils respond to more than changes in light.
Review. 1  Atoms have their electrons arranged in layers called shells. 2  In order to maintain electrical balance the number of electrons is equal to the number of protons in most elements.
Best Answer: It is the number of protons within the atom that defines what element it is. The electrons within an atom of the same element can change during reactions but it still remains the same element, and the same applies for neutrons. But the protons always stay the same.