Review the electron configuration of the inert gases. Review the maximum number of electrons which can be found in each of the energy levels, the last energy level in particular. Atoms which are classified as metals are defined and located, as well as those classified as non metals. The stability, the inert activity of the noble gases is due to the maximum electrons present in the last energy level of each atom, which is 8, except for helium which is 2. The group 1 atoms, lithium, sodium, and potassium are drawn with the electrons shown as numbers in each level, and as a dot in the last level. Each atom in this group has 1 electron in its last energy level. The concept of atomic charge neutrality was shown by subtracting the number of electrons from protons in each atom, arriving at a net charge of zero. Each group 1 atom was then sketched after "losing" the one electron in the outer level. The stability of each atom was based on its structure being now identical to one of the inert atoms. The number of electrons subtracted from protons at this point indicates an atom which exhibits a charge of +1. The atoms are now called Ions.