METALLOID

Together with the metals and nonmetals, the metalloids (in Greek metallon = metal and eidos = sort) form one of the three categories of chemical elements as classified by ionization and bonding properties. They have chemical properties intermediate between those of metals and nonmetals. For example, their oxides are often amphoteric. Their electronic properties vary from those of semiconductors (B,Si,Ge) to semimetals (eg. Sb). The concepts metalloid, semiconductor and semimetal should not be confused. Metalloid refers to the chemical properties of certain elements in relation to the periodic table. Semiconductor and semimetal refer to the physical properties of materials (including alloys, compounds) and there is only partial overlap between the two.

The known metalloids (and their atomic symbols) are:

• Boron (B)
• Silicon (Si)
• Germanium (Ge)
• Arsenic (As)
• Antimony (Sb)
• Tellurium (Te)
• Polonium (Po)
• Astatine (At)

In the periodic table, metalloids occur along the diagonal line from boron to polonium. Elements to the upper right of this line are nonmetals; elements to the lower left are metals.