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.
Mass number-atomic number = # neutrons. Determining the number of electrons-. The number of electrons in an element can change. For a neutral atom, the number of protons is exactly equal to the number of electrons.So the number of electrons is the same as the atomic number.ass number-atomic number = # neutrons. Determining the number of electrons-. The number of electrons in an element can change. For a neutral atom, the number of protons is exactly equal to the number of electrons.