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.
(A) atoms contain equal numbers of protons and neutrons (B) the mass of an atom is equal to the number of protons + the number of electrons (C) neutrons have a mass of 0 and a charge of 1 (D) to calculate the number of neutrons in an atom, use the mass in the periodic table (E) the atomic number is the number of electrons in an atom