This is a list of sources that each list metalloids: elements classified as metalloids. The sources are listed in chronological order. Lists of metalloids differ since there is no rigorous definition of metalloid (or its occasional alias, 'semi-metal'). Individual lists share common ground, with variations occurring at the margins. The elements most often regarded as metalloids are boron, silicon, germanium, arsenic, antimony and tellurium.[n 1] Wikipedia generally categorises these six as metalloids, with the addition of astatine. Other sources may subtract from this list or add a varying number of other elements.
Recognition status, as metalloids, of some elements in the p-block of the periodic table. Percentages are median appearance frequencies in the lists of metalloids.[n 2] The staircase-shaped line is a typical example of the arbitrary metal–nonmetal dividing line found on some periodic tables.
in n = 194 publications
194 = 100%
This table show which elements are included in each of 194 different lists of metalloids. A parenthesized symbol indicates an element whose inclusion in a particular metalloid list is qualified in some way by the author(s). The 'citations' rows show how many and what percentage of the authorities consider each element to be a metalloid, with qualified citations counted as one-half.
() Parenthesized symbols indicate elements whose inclusion in a particular metalloid list is qualified in some way by the author(s). It is counted as 0.5 citation.
There is an average of 7.15 elements per metalloid list.
Appearance frequency clusters
Clusters of elements and their appearance in the sources
Elements cited in the listed sources (as of August 2011; n = 194) have appearance frequencies that occur in clusters of comparable values. The diamonds in the graph mark the mean appearance frequency of each cluster. Cluster 1 (93%) = B, Si, Ge, As, Sb, Te; cluster 2 (44%) = Po, At; cluster 3 (24%) = Se; cluster 4 (9%) = C, Al; cluster 5 (5%) = Be, P, Bi; cluster 6 (3%) = Sn; and cluster 7 (1%) = H, Ga, S, I, Pb, Fl, Mc, Lv, Ts. The resulting geometric trend line has the formula y = 199.47e−0.7423x and an R2 value of 0.9962.[n 3]
Elements regarded as metalloids
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.[n 5] One or more of carbon, aluminium, phosphorus, selenium, tin or bismuth, these being periodic table neighbours of the elements commonly classified as metalloids, are sometimes recognised as metalloids.[n 6]
Selenium, in particular, is commonly designated as a metalloid in environmental chemistry[n 7] on account of similarities in its aquatic chemistry with that of arsenic and antimony.[n 8] There are fewer references to beryllium, in spite of its periodic table position adjoining the dividing line between metals and nonmetals. Isolated references in the literature can also be found to the categorisation of other elements as metalloids. These elements include: hydrogen, nitrogen,[n 9] sulfur,[n 10] zinc,[n 11] gallium,[n 12] iodine,[n 13] lead,[n 14] and radon[n 15] (citations are for references other than those listed above).
Goldsmith RH 1982, 'Metalloids', Journal of Chemical Education, vol. 59, no. 6, pp. 526–7 (526), doi:10.1021/ed059p526
Mann JB, Meek TL & Allen LC 2000, 'Configuration energies of the main group elements', Journal of the American Chemical Society, vol. 122, no. 12, pp. 2780–3 (2783), doi:10.1021ja992866e: Mann et al. refer to these elements as 'the recognized metalloids'.
Kotz JC, Treichel P & Weaver GC 2009, Chemistry and Chemical Reactivity, 7th ed., Brooks/Cole, Belmont, California, ISBN 1439041318
Rochow EG 1966, The metalloids, DC Heath and Company, Boston, pp. 7–8
Cobb HM 2012, Dictionary of Metals, ASM International, Materials Park, OH, p. 145, ISBN 9781615039784
Walker CH 2012, Organic Pollutants: An Ecotoxicological Perspective, 2nd ed., CRC Press, Boca Raton, FL, p. 163, ISBN 9781420062588
Whiten K, Davis R, Peck L & Stanley G 2014, Chemistry, 10th ed., Brooks/Cole Cengage Learning, Belmont, CA, p. 134, ISBN 9781133610663
^Selenium as a metalloid in environmental chemistry:
Meyer JS, Adams WJ, Brix KV, Luoma SM, Mount DR, Stubblefield WA & Wood CM (eds) 2005, Toxicity of dietborne metals to aquatic organisms, Proceedings from the Pellston Workshop on Toxicity of Dietborne Metals to Aquatic Organisms, 27 July–1 August 2002, Fairmont Hot Springs, British Columbia, Canada, Society of Environmental Toxicology and Chemistry, Pensacola, Florida, p. 284, ISBN 1880611708
Weiner ER 2013, Applications of Environmental Aquatic Chemistry: A Practical Guide, 3rd ed., CRC Press, Boca Raton, FL, p. 181, ISBN 9781439853320
^Similarities in the aquatic chemistry of selenium, arsenic, and antimony:
US Environmental Protection Agency 1988, Ambient aquatic life water quality criteria for antimony (III), draft, Office of Research and Development, Environmental Research Laboratories, Washington, p. 1
De Zuane J 1997, Handbook of drinking water quality, 2nd ed., John Wiley & Sons, New York, p. 93, ISBN 047128789X
Uden PC 2005, 'Speciation of selenium,' in R Cornelis, J Caruso, H Crews & K Heumann (eds), Handbook of elemental speciation II: Species in the environment, food, medicine and occupational health, John Wiley & Sons, Chichester, pp. 346–65 (347–8), ISBN 0470855983
Dev N 2008, 'Modelling selenium fate and transport in Great Salt Lake Wetlands' PhD dissertation, University of Utah, ProQuest, Ann Arbor, Michigan, pp. 2–3, ISBN 054986542X
Rausch MD 1960, 'Cyclopentadienyl compounds of metals and metalloids', Journal of Chemical Education, vol. 37, no. 11, pp. 568–78, doi:10.1021/ed037p568
Hampel CA & Hawley GG 1966, The encyclopedia of chemistry, 3rd ed., Van Nostrand Reinhold, New York,p. 950
Stein L 1985, 'New evidence that radon is a metalloid element: ion-exchange reactions of cationic radon', Journal of the Chemical Society, Chemical Communications, vol. 22, pp. 1631–2, doi:10.1039/C39850001631
Stein L 1987, 'Chemical properties of radon' in PK Hopke (ed.) 1987, Radon and its decay products: Occurrence, properties, and health effects, American Chemical Society, Washington DC, pp. 240–51 (240, 247–8), ISBN 0841210152
^Simmons LM 1947, 'A modification of the periodic table', Journal of Chemical Education, December, pp. 588–591 (589) doi:10.1021/ed024p588
^Pauling, L (1949). General chemistry. WH Freeman, San Francisco. p. 65.
^Szabó ZG & Lakatos B 1954, 'The new form of the periodic table and new periodic functions', Acta Chimica Academiae Scientiarum Hungaricae, IV 2–4, pp. 129–149 (133)
^Dull CE, Metcalfe HC & Williams JE 1958, Modern chemistry, Henry Holt and Company, New York, pp. 59–60, 62
^Frey PR 1958, College chemistry, 2nd ed., Prentice-Hall, Englewood Cliffs, NJ, p. 118
^Johnstone RT & Miller SE 1960, Occupational diseases and industrial medicine, Saunders, Philadelphia, p. 262
^Edwards JO, Ellison HR, Luaro CG & Lorand JP 1961, 'Factors which influence the stability of anionic complexes', in S Kirschner, Advances in the chemistry of the coordination compounds: Proceedings of the sixth international conference on coordination chemistry, Macmillan, New York, pp. 230–237 (230)
^Bond GC 1962, Catalysis by metals, Academic Press, London, p. 8
^Swift EH & Schaefer WP 1962, Qualitative elemental analysis, WH Freeman, San Francisco, p. 100
^Hoffman KB 1963, Chemistry for the applied sciences, Prentice-Hall, Englewood Cliffs, NJ, p. 34
A chemical element is a species of atom having the same number of protons in their atomic nuclei (that is, the same atomic number, or Z). For example, the atomic number of oxygen is 8, so the element oxygen consists of all atoms which have exactly 8 protons.
118 elements have been identified, of which the first 94 occur naturally on Earth with the remaining 24 being synthetic elements. There are 80 elements that have at least one stable isotope and 38 that have exclusively radionuclides, which decay over time into other elements. Iron is the most abundant element (by mass) making up Earth, while oxygen is the most common element in the Earth's crust.Chemical elements constitute all of the ordinary matter of the universe. However astronomical observations suggest that ordinary observable matter makes up only about 15% of the matter in the universe: the remainder is dark matter; the composition of this is unknown, but it is not composed of chemical elements.
The two lightest elements, hydrogen and helium, were mostly formed in the Big Bang and are the most common elements in the universe. The next three elements (lithium, beryllium and boron) were formed mostly by cosmic ray spallation, and are thus rarer than heavier elements. Formation of elements with from 6 to 26 protons occurred and continues to occur in main sequence stars via stellar nucleosynthesis. The high abundance of oxygen, silicon, and iron on Earth reflects their common production in such stars. Elements with greater than 26 protons are formed by supernova nucleosynthesis in supernovae, which, when they explode, blast these elements as supernova remnants far into space, where they may become incorporated into planets when they are formed.The term "element" is used for atoms with a given number of protons (regardless of whether or not they are ionized or chemically bonded, e.g. hydrogen in water) as well as for a pure chemical substance consisting of a single element (e.g. hydrogen gas). For the second meaning, the terms "elementary substance" and "simple substance" have been suggested, but they have not gained much acceptance in English chemical literature, whereas in some other languages their equivalent is widely used (e.g. French corps simple, Russian простое вещество). A single element can form multiple substances differing in their structure; they are called allotropes of the element.
When different elements are chemically combined, with the atoms held together by chemical bonds, they form chemical compounds. Only a minority of elements are found uncombined as relatively pure minerals. Among the more common of such native elements are copper, silver, gold, carbon (as coal, graphite, or diamonds), and sulfur. All but a few of the most inert elements, such as noble gases and noble metals, are usually found on Earth in chemically combined form, as chemical compounds. While about 32 of the chemical elements occur on Earth in native uncombined forms, most of these occur as mixtures. For example, atmospheric air is primarily a mixture of nitrogen, oxygen, and argon, and native solid elements occur in alloys, such as that of iron and nickel.
The history of the discovery and use of the elements began with primitive human societies that found native elements like carbon, sulfur, copper and gold. Later civilizations extracted elemental copper, tin, lead and iron from their ores by smelting, using charcoal. Alchemists and chemists subsequently identified many more; all of the naturally occurring elements were known by 1950.
The properties of the chemical elements are summarized in the periodic table, which organizes the elements by increasing atomic number into rows ("periods") in which the columns ("groups") share recurring ("periodic") physical and chemical properties. Save for unstable radioactive elements with short half-lives, all of the elements are available industrially, most of them in low degrees of impurities.
This is a list of articles that are lists of list articles on the English Wikipedia. In other words, each of the articles linked here is an index to multiple lists on a topic. Some of the linked articles are themselves lists of lists of lists. This article is also a list of lists.
A metalloid is a type of chemical element which has properties in between, or that are a mixture of, those of metals and nonmetals. 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. Five elements are less frequently so classified: carbon, aluminium, selenium, polonium, and astatine. On a standard periodic table, all eleven elements are located in a diagonal region of the p-block extending from boron at the upper left to astatine at lower right. Some periodic tables include a dividing line between metals and nonmetals and the metalloids may be found close to this line.
Typical metalloids have a metallic appearance, but they are brittle and only fair conductors of electricity. Chemically, they behave mostly as nonmetals. They can form alloys with metals. Most of their other physical properties and chemical properties are intermediate in nature. 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 are sometimes called semimetals, a practice that has been discouraged, as the term semimetal has a different meaning in physics than in chemistry. In physics, it specifically refers to the electronic band structure of a substance.
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