A metalloid is any chemical element which has properties in between those of metals and nonmetals, or that has a mixture of them.There is neither a standard definition of a metalloid nor complete agreement on the elements appropriately classified as such.They also said that metalloids are typically semiconductors, though antimony and arsenic (semimetals from a physics perspective) have electrical conductivities approaching those of metals.Selenium and polonium are suspected as not in this scheme, while astatine's status is uncertain.listed twelve (Emsley's plus boron, carbon, silicon, selenium, bismuth, polonium, moscovium and livermorium).On average, seven elements are included in such lists; individual classification arrangements tend to share common ground and vary in the ill-defined used three criteria to describe the six elements commonly recognised as metalloids: metalloids have ionization energies around 200 kcal/mol (837 k J/mol) and electronegativity values close to 2.0.Five elements are less frequently so classified: carbon, aluminium, selenium, polonium, and astatine.
With some irregularities, atoms therefore become smaller, ionization energy increases, and there is a gradual change in character, across a period, from strongly metallic, to weakly metallic, to weakly nonmetallic, to strongly nonmetallic elements.
This exception arises due to competing horizontal and vertical trends in the nuclear charge.
Going along a period, the nuclear charge increases with atomic number as do the number of electrons.
This is a generic definition that draws on metalloid attributes consistently cited in the literature.
The term metalloid also has been used for elements that exhibit metallic lustre and electrical conductivity, and that are amphoteric, such as arsenic, antimony, vanadium, chromium, molybdenum, tungsten, tin, lead, and aluminium.
This can be found, in varying configurations, on some periodic tables.