Metalloid

Metalloid
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Metalloid is a term used in chemistry when classifying the chemical elements. On the basis of their general physical and chemical properties, nearly every element in the periodic table can be termed either a metal or a non-metal - however a few elements with intermediate properties are referred to as metalloids. (In Greek metallon = metal and eidos = sort)

There is no rigorous definition of the term, however the following properties are usually considered characteristic of metalloids:

metalloids often form amphoteric oxides.
metalloids often behave as semiconductors (B,Si,Ge) to semimetals (eg. Sb).
The concepts of metalloid and semiconductor should not be confused. Metalloid refers to the properties of certain elements in relation to the periodic table. Semiconductor refers to the physical properties of materials (including alloys, compounds) and there is only partial overlap between the two.

The following elements are generally considered metalloids:[1]

Boron (B)
Silicon (Si)
Germanium (Ge)
Arsenic (As)
Antimony (Sb)
Tellurium (Te)
Polonium (Po)
Some allotropes of elements exhibit more pronounced metal, metalloid or non-metal behavior than others. For example, for the element carbon, its diamond allotrope is clearly non-metallic, however the graphite allotrope displays limited electric conductivity more characteristic of a metalloid. Phosphorus, tin, selenium and bismuth also have allotropes which display borderline behavior.

In the standard layout of the periodic table, metalloids occur along the diagonal line through the p block from boron to astatine. Elements to the upper right of this line display increasing nonmetallic behaviour; elements to the lower left display increasing metallic behaviour. This line is called the "stair-step" or "staircase." The poor metals are to the left and down and the nonmetals are to the right and up. In addition, the halogens are found at the right.

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


[edit] Reference
^ ACS Periodic Table. [1]




[hide]v • d • ePeriodic tables
Layouts Standard · Vertical · Full names · Names and atomic masses · Text for last · Huge table · Metals and nonmetals · Blocks · Valences · Inline f-block · 218 elements · Electron configurations · Atomic masses · Electronegativities · Alternatives
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
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