1) Metal character increases down a group and decreases across a period on the periodic table. Metals have low ionization energies and form cations by losing electrons. 2) Most metal oxides are basic, while most nonmetal oxides are acidic. When nonmetal oxides react with water, acids are formed. 3) The octet rule states that atoms bond to achieve a full outer shell of 8 electrons. Atoms gain, lose or share electrons to achieve an octet configuration.