Metals are generally lustrous, are able to conduct heat and electricity, have high melting points, are malleable, remain solid at room temperature and appear opaque in thin cross-sections. Non-metals have a dull appearance, are brittle, cannot conduct heat and electricity well, are transparent in thin cross-sections and can exist as solids, liquids or gases at room temperature.
Physical and non-physical attributes are used to distinguish between metals and non-metals on the periodic table of elements. Metals are chemically different from non-metals due to the fact that they corrode easily, form basic oxides and lose electrons easily. Metals are prone to oxidative damage, such as rust and tarnish. Non-metals form acidic oxides, are good oxidizing agents and readily gain or share valence electrons. The BBC states that of the metals, iron, cobalt and nickel contain magnetic properties. None of the non-metals are magnetic. Metals have a high density and feel heavy, while non-metals have a low density. Metals make a ringing sound when hit, and non-metals make a dull sound.
There is a class of elements located in the middle of the periodic table of elements, called metalloids or semimetals, which are considered to exhibit qualities of both types of elements. These include boron, silicon, germanium, arsenic, antimony, tellurium and polonium.