Isotope atoms with the same number of protons and electrons, but different numbers of neutrons. A cartoon of atoms. Electrons are outside the nucleus, and determine properties of the atom. Electrons determine chemical properties of elements. Chemical reactions involve sharing or exchanging electrons.
Electrons move about the nucleus in atomic orbitals.
Absorption of energy can cause an electron to move up to a higher energy level. The atom is stable when the outermost energy level of most atoms has eight electrons. Electrons can be transferred carrying energy to another molecule. H atom can carry electrons for transfering energy. Oxygen and nitrogen are electronegative, having strong affinities for electrons.