Cost of carbon dating wood

17-Oct-2015 10:10 posted by benjy678 | Leave a comment

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.

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Five elements are less frequently so classified: carbon, aluminium, selenium, polonium, and astatine.On a standard periodic table, all eleven are in a diagonal area in the p-block extending from boron at the upper left to astatine at lower right, along the dividing line between metals and nonmetals shown on some periodic tables. Most of their other physical and chemical properties are intermediate in nature.Typical metalloids have a metallic appearance, but they are brittle and only fair conductors of electricity. Metalloids are usually too brittle to have any structural uses.They and their compounds are used in alloys, biological agents, catalysts, flame retardants, glasses, optical storage and optoelectronics, pyrotechnics, semiconductors, and electronics.The electrical properties of silicon and germanium enabled the establishment of the semiconductor industry in the 1950s and the development of solid-state electronics from the early 1960s.The term metalloid originally referred to nonmetals.

Its more recent meaning, as a category of elements with intermediate or hybrid properties, became widespread in 1940–1960.

Metalloids sometimes are called semimetals, a practice that has been discouraged, A metalloid is an element with properties in between, or that are a mixture of, those of metals and nonmetals, and which is therefore hard to classify as either a metal or a nonmetal.

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.

Despite the lack of specificity, the term remains in use in the literature of chemistry.

The six commonly recognised metalloids are boron, silicon, germanium, arsenic, antimony, and tellurium.

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