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The elements commonly classified as metalloids are boron, silicon, germanium, arsenic, antimony and tellurium. [n 4] The status of polonium and astatine is not settled. Most authors recognise one or the other, or both, as metalloids; Herman, Hoffmann and Ashcroft, on the basis of relativistic modelling, predict astatine will be a monatomic metal.
[412] [n 43] In organic chemistry, carbon can form complex cations – termed carbocations – in which the positive charge is on the carbon atom; examples are CH + 3 and CH + 5, and their derivatives. [413] Graphite is an established solid lubricant and behaves as a semiconductor in a direction perpendicular to its planes. [407]
The chemical elements can be broadly divided into metals, metalloids, and nonmetals according to their shared physical and chemical properties.All elemental metals have a shiny appearance (at least when freshly polished); are good conductors of heat and electricity; form alloys with other metallic elements; and have at least one basic oxide.
As a metalloid, its chemistry is largely covalent in nature, noting it can form brittle alloys with metals, and has an extensive organometallic chemistry. Most alloys of arsenic with metals lack metallic or semimetallic conductivity. The common oxide of arsenic (As 2 O 3) is acidic but weakly amphoteric. Antimony, showing its brilliant lustre
Hydrogen is again placed by itself on account of its uniqueness. The remaining nonmetals are divided into metalloids, nonmetals, (referred to as "quintessential nonmetals"), halogens, and noble gases. Since the metalloids abut the post-transition or "poor" metals, they might be renamed as "poor non-metals". [11]
Organometallic chemistry is the study of organometallic compounds, chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal, including alkali, alkaline earth, and transition metals, and sometimes broadened to include metalloids like boron, silicon, and selenium, as well.
These sets usually do not aim to cover the whole periodic table (as for example period does), and often overlap or have boundaries that differ between authors. Some examples: Metals and nonmetals; Metalloids – Variously-defined group of elements with properties intermediate between metals and nonmetals. In alphabetic order:
Bioinorganic chemistry is a field that examines the role of metals in biology. Bioinorganic chemistry includes the study of both natural phenomena such as the behavior of metalloproteins as well as artificially introduced metals, including those that are non-essential , in medicine and toxicology .