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.
Electrons are negatively charged, protons have a positive charge, and neutrons are neutral/have no charge. The atomic number of the element means the number of protons it has. For example, all oxygen atoms have eight protons;... An element's identity is determined by the number of protons it has. The basic structure of an atom is that there are protons and neutrons in the nucleus, and electrons that are orbiting at set distances from the nucleus.