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.
Copper The number of protons in an atom of an element is the same as the atomic number. So finding the number of protons in an atom just consists of looking at a periodic table. Copper's atomic number is 29, so it has 29 protons. In a neutral atom, the number of electrons will equal and balance the number of protons, so it would also be 29 electrons.