An atom consists of a ______ of protons and ____ surrounded by a cloud of _____. For each atom, the number of _____ is the atomic ______. Atoms with the same _____ number constitute an element. Atoms of a single ____ that have different numbers of ______ are called ______. Electrons, which determine the chemical _____ of an element, are located about a nucleus in ___ representing discrete energy levels. No ____ can contain more than 2 _____. Many orbitals may have the same energy _____ and thus contain ____ with the same energy.
