Metals have one to three electrons in their outer shell, whereas non-metals have four to eight electrons. Another difference is that metals tend to lose their valence electrons, but non-metals share or gain valence electrons. Where metals form oxides which are basic, non-metals form oxides which are acidic.What are the metals and nonmetals in the periodic table?
The metalloids or semimetals are located along the line between the metals and nonmetals in the periodic table. The metalloids are boron, silicon, germanium, arsenic, antimony, and tellurium. Other elements less commonly recognized as metalloids include carbon, aluminium, selenium, polonium and astatine.