Metalloid

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Together with the metals and nonmetals, the metalloids (in Greek metallon = metal and eidos = sort - also called semimetals) form one of the three categories of chemical elements as classified by ionization and bonding properties. They have properties intermediate between those of metals and nonmetals. There is no unique way of distinguishing a metalloid from a true metal but the most common is that metalloids are usually semiconductors rather than conductors.

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.

13 14 15 16 17
B
Boron C
Carbon N
Nitrogen O
Oxygen F
Fluorine
Al
Aluminium Si
Silicon P
Phosphorus S
Sulfur Cl
Chlorine
Ga
Gallium Ge
Germanium As
Arsenic Se
Selenium Br
Bromine
In
Indium Sn
Tin Sb
Antimony Te
Tellurium I
Iodine
Tl
Thallium Pb
Lead Bi
Bismuth Po
Polonium At
Astatine

13	14	15	16	17
B Boron	C Carbon	N Nitrogen	O Oxygen	F Fluorine
Al Aluminium	Si Silicon	P Phosphorus	S Sulfur	Cl Chlorine
Ga Gallium	Ge Germanium	As Arsenic	Se Selenium	Br Bromine
In Indium	Sn Tin	Sb Antimony	Te Tellurium	I Iodine
Tl Thallium	Pb Lead	Bi Bismuth	Po Polonium	At Astatine

Semi-metallic behaviour is not confined to the elements, but is also found in alloys and compounds. Mercury(II) telluride is one example.

One definition of semi-metallic behavior would be if the conduction band and valence band overlap. This is also true of metals, so semi-metals must additionally have a relatively low carrier density.

Periodic tables
Standard table \| Vertical table \| Table with names \| Names and atomic masses (large) \| Names and atomic masses (small) \| Names and atomic masses (text only) \| Inline F-block \| Elements to 218 \| Electron configurations \| Metals and nonmetals \| Table by blocks
Lists of elements
Name \| Atomic symbol \| Atomic number \| Boiling point \| Melting point \| Density \| Atomic mass
Groups: 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 10 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18
Periods: 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9
Series: Alkalis - Alkaline earths - Lanthanides - Actinides - Transition metals - Poor metals - Metalloids - Nonmetals - Halogens - Noble gases
Blocks: s-block - p-block - d-block - f-block - g-block

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