Which Elements Are Metalloids?

Abstract

The results of a recent survey of 194 metalloid lists are consistent with a three-criterion description of metalloids published over 35 years ago. The classifications of selenium, polonium, and astatine, and other metalloid-like elements, are briefly reviewed in this light.

Organising the metals and nonmetals

“…The elements commonly recognised as metalloids are boron, silicon, germanium, arsenic, antimony and tellurium (Vernon 2013). As the weakest of the nonmetals they are assigned positive oxidation states in their compounds with nonmetals, and negative oxidation states in their compounds with most metals.…”

Performance of metal–organic frameworks for the adsorptive removal of potentially toxic elements in a water system: a critical review

“…The six elements, boron, silicon, germanium, arsenic, antimony, and tellurium commonly recognized as metalloids. 92 Not many MOF studies have investigated the removal of metalloids, but of those that have, arsenic has been a signicant focus. The limited studies available have focused on the simultaneous removal of multivalent metalloids.…”

“…Adsorption of arsenic into the MOF was conrmed using transmission electron microscopy (TEM) and FTIR to show an IR band at 824 cm À1 and interior sites that corresponded to Fe-O-As groups. 92,95 Zeolitic imidazolate framework-8 (ZIF-8) for arsenic uptake, has achieved an adsorption capacity of 49.5 mg g À1 of As(V) and 60 mg g À1 of As(III) at neutral pH signifying high removal potential is for As(III). Obviously, As(III) achieves the highest adsorption capacity compared to As(V) due to the high loading concentration of As(III) relative to As(V).…”

Viewpoint: Metalloids—An Electronic Band Structure Perspective

“…Furthermore, the structure of At is unknown. If isostructural to I 2 , At is predicted to be a semiconductor . If, however, it possesses a face‐centered cubic structure, and is not diatomic like the other halogens, a metallic if not superconducting state is predicted .…”