This is a list of 194 sources that list elements classified as metalloids. The sources are listed in chronological order. Lists of metalloids differ since there is no rigorous widely accepted 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] Other sources may subtract from this list, add a varying number of other elements, or both.
13 | 14 | 15 | 16 | 17 | ||
---|---|---|---|---|---|---|
2 | B Boron | C Carbon | N Nitrogen | O Oxygen | F Fluorine | |
3 | Al Aluminium | Si Silicon | P Phosphorus | S Sulfur | Cl Chlorine | |
4 | Ga Gallium | Ge Germanium | As Arsenic | Se Selenium | Br Bromine | |
5 | In Indium | Sn Tin | Sb Antimony | Te Tellurium | I Iodine | |
6 | Tl Thallium | Pb Lead | Bi Bismuth | Po Polonium | At Astatine | |
Commonly recognized (86–99%): B, Si, Ge, As, Sb, Te Irregularly recognized (40–49%): Po, At Less commonly recognized (24%): Se Rarely recognized (8–10%): C, Al (All other elements cited in less than 6% of sources) Arbitrary metal-nonmetal dividing line: between Be and B, Al and Si, Ge and As, Sb and Te, Po and At | ||||||
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. |
Element | Citations | Frequency | |
---|---|---|---|
in n = 194 publications | 194 = 100% | ||
Arsenic | As | 191.5 | 99% |
Tellurium | Te | 190.5 | 98% |
Germanium | Ge | 184.5 | 95% |
Silicon | Si | 183.5 | 95% |
Antimony | Sb | 169.5 | 87% |
Boron | B | 166 | 86% |
Polonium | Po | 94.5 | 49% |
Astatine | At | 77 | 40% |
Selenium | Se | 46 | 24% |
Aluminium | Al | 18 | 9.3% |
Carbon | C | 16.5 | 8.5% |
Bismuth | Bi | 11.5 | 5.9% |
Phosphorus | P | 10 | 5.2% |
Beryllium | Be | 7.5 | 3.9% |
Tin | Sn | 5.5 | 2.8% |
Sulfur | S | 3 | 1.5% |
Livermorium | Lv | 3 | 1.5% |
Iodine | I | 2.5 | 1.3% |
Flerovium | Fl | 1 | 0.5% |
Gallium | Ga | 1 | 0.5% |
Hydrogen | H | 1 | 0.5% |
Lead | Pb | 1 | 0.5% |
Moscovium | Mc | 1 | 0.5% |
Tennessine | Ts | 1 | 0.5% |
This table shows 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.
Citations as metalloid by element | |||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Element | Arsenic | Tellurium | Germanium | Silicon | Antimony | Boron | Polonium | Astatine | Selenium | Aluminium | Carbon | Bismuth | Phosphorus | Beryllium | Tin | Sulfur | Livermorium | Iodine | Other | Count | |
As | Te | Ge | Si | Sb | B | Po | At | Se | Al | C | Bi | P | Be | Sn | S | Lv | I | avg | |||
Citations (with qualification)* | 191.5 (1) | 190.5 (1) | 184.5 (3) | 183.5 (1) | 169.5 (3) | 166 (2) | 94.5 (5) | 77 (6) | 46 (4) | 18 (2) | 16.5 (3) | 11.5 (1) | 10 (2) | 7.5 (1) | 5.5 (1) | 3 (0) | 3 (0) | 2.5 (1) | 6 (0)'' | 7.15 | |
(% out of 194) | 99% | 98% | 95% | 95% | 87% | 86% | 49% | 40% | 24% | 9.3% | 8.5% | 5.9% | 5.2% | 3.9% | 2.8% | 1.5% | 1.5% | 1.3% | 3.1% | ||
Source | Yr | ||||||||||||||||||||
Simmons [1] | 1947 | As | Te | Sb | Se | 4 | |||||||||||||||
Pauling [2] | 1949 | As | Te | Ge | Si | Sb | B | Po | 7 | ||||||||||||
Szabó & Lakatos [3] | 1954 | As | Te | Ge | Si | Sb | B | Po | At | Al | Be | 10 | |||||||||
Dull, Metcalfe & Williams [4] | 1958 | As | Te | Ge | Si | Sb | B | Po | At | Al | 9 | ||||||||||
Frey [5] | 1958 | As | Te | Ge | Si | Sb | B | Po | 7 | ||||||||||||
Johnstone & Miller [6] | 1960 | As | Te | Ge | Si | Sb | B | Se | C | P | 9 | ||||||||||
Edwards et al. [7] | 1961 | As | Te | Ge | Si | Sb | B | Se | I | 8 | |||||||||||
Bond [8] | 1962 | As | Te | Ge | Si | Sb | B | Po | 7 | ||||||||||||
Swift & Schaefer [9] | 1962 | As | Ge | Si | Sb | B | Bi | 6 | |||||||||||||
Hoffman [10] | 1963 | As | Te | Ge | Si | Sb | B | Be | 7 | ||||||||||||
Nathans [11] | 1963 | As | Te | Ge | Si | Sb | B | At | 7 | ||||||||||||
Bailar, Moeller & Kleinberg [12] | 1965 | As | Te | Ge | Se | 4 | |||||||||||||||
Selwood [13] | 1965 | As | Te | Ge | Si | Sb | B | Po | At | Al | Bi | Sn | Ga | 12 | |||||||
Bassett et al. [14] | 1966 | Te | Ge | Si | Sb | B | Po | Al | Be | 8 | |||||||||||
Hultgren [15] | 1966 | As | Te | Ge | Si | Sb | Se | C | 7 | ||||||||||||
Metcalfe, Williams & Castka [16] | 1966 | As | Te | Ge | Si | Sb | B | Po | (Al) | 7.5 | |||||||||||
Rochow [17] | 1966 | As | Te | Ge | Si | Sb | B | (Po) | (At) | (Se) | (C) | (Bi) | (P) | 9 | |||||||
Mahan [18] | 1967 | As | Te | Ge | Si | B | 5 | ||||||||||||||
Paul, King & Farinholt [19] | 1967 | As | Te | Ge | Si | Sb | Se | 6 | |||||||||||||
Siebring [20] | 1967 | As | Te | Ge | Si | Sb | B | Po | Al | 8 | |||||||||||
Cotton & Lynch [21] | 1968 | As | Te | Ge | Si | Sb | B | At | Se | C | 9 | ||||||||||
Dunstan [22] | 1968 | As | Te | (Ge) | Sb | Po | Al | Bi | Be | Sn | Pb | 7.5 | |||||||||
Tyrell & Warren [23] | 1968 | As | Te | (Ge) | Si | (Sb) | B | (Po) | At | (Se) | (Al) | (C) | (P) | (I) | 9.5 | ||||||
Williams, Embree & DeBey [24] | 1968 | As | Te | Ge | Si | Sb | B | Po | Al | 8 | |||||||||||
Chedd [25] | 1969 | As | Te | Ge | Si | Sb | B | Po | At | 8 | |||||||||||
Hägg [26] | 1969 | As | Te | Ge | Sb | At | Sn | 6 | |||||||||||||
Holum [27] | 1969 | As | Te | Ge | Si | Sb | B | Po | At | Al | 9 | ||||||||||
Hunter [28] | 1969 | As | Te | Si | Sb | Se | 5 | ||||||||||||||
Moody [29] | 1969 | As | Te | Ge | Si | Sb | B | Po | At | Al | Be | 10 | |||||||||
Dickerson, Gray & Haight [30] | 1970 | As | Te | Ge | Si | Sb | B | 6 | |||||||||||||
Hardwick & Knobler [31] | 1970 | As | Te | Ge | Si | Sb | B | 6 | |||||||||||||
Williams, Embree & DeBay [32] | 1970 | As | Te | Ge | Si | Sb | B | Po | Al | Be | 9 | ||||||||||
Dickson [33] | 1971 | As | Te | Ge | Si | Sb | Po | 6 | |||||||||||||
Emsley [34] | 1971 | As | Te | Ge | Sb | 4 | |||||||||||||||
Nitz & Dhonau [35] | 1971 | As | Te | Ge | Si | Sb | B | Po | 7 | ||||||||||||
Pimentel & Spratley [36] | 1971 | As | Te | Ge | Si | Sb | B | (Po) | (At) | Se | C | 9 | |||||||||
Barrow [37] | 1972 | As | Te | Ge | Si | B | 5 | ||||||||||||||
Choppin & Johnsen [38] | 1972 | As | Te | Ge | Si | Sb | B | Se | 7 | ||||||||||||
Horvath [39] | 1973 | As | Te | Ge | Si | Sb | B | Po | 7 | ||||||||||||
Pascoe [40] | 1973 | Te | Ge | Si | B | At | Se | C | P | 8 | |||||||||||
Seager & Stoker [41] | 1973 | As | Te | Ge | Si | Sb | B | Po | At | Al | Be | 10 | |||||||||
Allen & Keefer [42] | 1974 | As | Te | Ge | Si | Sb | B | At | Se | 8 | |||||||||||
Andrews [43] | 1974 | As | Te | Si | B | At | 5 | ||||||||||||||
Day & Johnson [44] | 1974 | As | Te | Ge | Si | Sb | Po | At | 7 | ||||||||||||
Dickson [45] | 1974 | As | Te | Ge | Si | Sb | Po | At | 7 | ||||||||||||
Duffy [46] | 1974 | As | Te | Ge | Sb | Se | 5 | ||||||||||||||
Fuller [47] | 1974 | As | Te | Ge | Si | B | Se | C | 7 | ||||||||||||
Nordmann [48] | 1974 | As | Te | Ge | Si | B | Po | At | Se | 8 | |||||||||||
O'Connor [49] | 1974 | As | Te | Ge | Si | Sb | B | Po | 7 | ||||||||||||
Rock & Gerhold [50] | 1974 | As | Te | Ge | Si | Sb | B | Po | At | 8 | |||||||||||
Pauling & Pauling [51] | 1975 | As | Te | Ge | Si | Sb | B | Po | 7 | ||||||||||||
Hearst & Ifft [52] | 1976 | As | Te | Ge | Si | Sb | B | Se | 7 | ||||||||||||
Tyler Miller [53] | 1976 | As | Te | Ge | Si | Sb | B | Po | At | Al | H | 10 | |||||||||
Waser, Trueblood & Knobler [54] | 1976 | As | Te | Ge | Si | Sb | B | Po | 7 | ||||||||||||
Bloomfield [55] | 1977 | As | Te | Ge | Si | Sb | B | Po | At | Al | 9 | ||||||||||
Ucko [56] | 1977 | As | Te | Ge | Si | Sb | B | Po | At | Al | 9 | ||||||||||
Hill & Holman [57] | 1978 | As | Te | Ge | Si | B | (C) | 5.5 | |||||||||||||
Coxon, Fergusson & Phillips [58] | 1980 | As | Te | Ge | Si | (Sb) | B | At | (Be) | 7 | |||||||||||
Warrena & Geballe [59] | 1981 | As | Te | Si | B | At | Se | C | P | S | 9 | ||||||||||
Walters [60] | 1982 | As | Te | Ge | Si | B | 5 | ||||||||||||||
Edwards & Sienko [61] | 1983 | As | Te | Ge | Sb | Po | (At) | 5.5 | |||||||||||||
Holtzclaw, Robinson & Nebergall [62] | 1984 | As | Te | Ge | Si | Sb | B | Po | At | 8 | |||||||||||
Boikess & Edelson [63] | 1985 | As | Te | Ge | Si | B | 5 | ||||||||||||||
Peters [64] | 1986 | As | Te | Ge | Si | Sb | B | Po | At | 8 | |||||||||||
Hibbert & James [65] | 1987 | As | Te | Ge | Si | Sb | Po | Bi | 7 | ||||||||||||
Jones et al. [66] | 1987 | As | Te | Ge | Si | Sb | B | Po | At | 8 | |||||||||||
McQuarrie & Rock [67] | 1987 | As | Te | Ge | Si | Sb | B | Po | At | 8 | |||||||||||
Wulfsberg [68] | 1987 | As | Te | Ge | Si | Sb | B | Se | 7 | ||||||||||||
Thayer [69] | 1988 | As | Te | Ge | Si | B | P | 6 | |||||||||||||
Whitten, Gailey & Davis [70] | 1988 | As | Te | Ge | Si | Sb | B | Po | At | Al | 9 | ||||||||||
Bailar et al. [71] | 1989 | As | Te | Ge | Si | Sb | B | Se | 7 | ||||||||||||
Gill [72] | 1989 | As | Te | Ge | Si | Sb | B | 6 | |||||||||||||
Malone [73] | 1989 | As | Te | Ge | Si | Sb | B | Po | At | 8 | |||||||||||
Petrucci [74] | 1989 | As | Te | Ge | Si | Sb | Po | At | 7 | ||||||||||||
Puddephatt & Monaghan [75] | 1989 | As | Te | Ge | Si | Sb | B | 6 | |||||||||||||
Scott [76] | 1989 | As | Te | Ge | Si | Sb | B | 6 | |||||||||||||
Segal [77] | 1989 | As | Te | Ge | Si | Sb | B | Po | 7 | ||||||||||||
Oxtoby, Nachtrieb & Freeman [78] | 1990 | As | Te | Ge | Si | Sb | B | Po | At | 8 | |||||||||||
Atkins & Beran [79] | 1990 | As | Te | Ge | Si | Sb | Po | 6 | |||||||||||||
Ebbing & Wrighton [80] | 1993 | As | Te | Ge | Si | Sb | B | At | 7 | ||||||||||||
Zumdahl [81] | 1993 | As | Te | Ge | Si | Sb | B | Po | At | 8 | |||||||||||
Birk [82] | 1994 | As | Te | Ge | Si | Sb | B | Po | 7 | ||||||||||||
Smith [83] | 1994 | As | Te | Ge | Si | Sb | B | 6 | |||||||||||||
AAE [84] | 1996 | As | Te | Ge | Si | Sb | B | Se | 7 | ||||||||||||
Brady & Holum [85] | 1996 | As | Te | Ge | Si | Sb | B | Po | At | 8 | |||||||||||
Harrison & de Mora [86] | 1996 | As | Te | Ge | Si | B | 5 | ||||||||||||||
Hook & Post [87] | 1996 | As | Te | Ge | Si | Sb | B | Po | At | 8 | |||||||||||
Atkins & Jones [88] | 1997 | As | Te | Ge | Si | Sb | Po | 6 | |||||||||||||
Dayah [89] | 1997 | As | Te | Ge | Si | Sb | B | Po | 7 | ||||||||||||
Mingos [90] | 1998 | As | Te | Ge | Si | Sb | B | Po | 7 | ||||||||||||
Joesten & Wood [91] | 1999 | As | Te | Ge | Si | Sb | B | 6 | |||||||||||||
Kremer [92] | 1999 | As | Te | Ge | Si | Sb | B | 6 | |||||||||||||
Thompson [93] | 1999 | As | Te | Ge | Si | Sb | B | 6 | |||||||||||||
Umland & Bellama [94] | 1999 | As | Te | Ge | Si | B | At | Se | 7 | ||||||||||||
Callister [95] | 2000 | As | Te | Ge | Si | B | Se | C | 7 | ||||||||||||
Enloe [96] | 2000 | As | Te | Si | B | At | 5 | ||||||||||||||
Mann, Meek & Allen [97] | 2000 | As | Te | Ge | Si | Sb | B | Po | Bi | 8 | |||||||||||
Phillips, Stozak & Wistrom [98] | 2000 | As | Te | Ge | Si | Sb | B | Po | At | 8 | |||||||||||
Ryan [99] | 2000 | As | Te | Ge | Si | B | 5 | ||||||||||||||
Hawkes [100] | 2001 | As | Te | Ge | Sb | Se | Bi | 6 | |||||||||||||
Lewis & Evans [101] | 2001 | As | Te | Ge | Si | Sb | B | Po | 7 | ||||||||||||
Masterton & Hurley [102] | 2001 | As | Te | Ge | Si | Sb | B | 6 | |||||||||||||
Barrett [103] | 2002 | (As) | (Te) | (Ge) | (Si) | (Sb) | (B) | (Se) | 3.5 | ||||||||||||
Chang [104] | 2002 | As | Te | Ge | Si | Sb | B | Po | At | Lv | Ts | 10 | |||||||||
Harding, Johnson & Janes [105] | 2002 | As | Te | Ge | Si | Sb | 5 | ||||||||||||||
Johnson [106] | 2002 | As | Te | Ge | Si | Sb | At | 6 | |||||||||||||
Rodgers [107] | 2002 | As | Te | Ge | Si | Sb | B | At | 7 | ||||||||||||
Szefer [108] | 2002 | As | Te | Ge | Si | Sb | Se | 6 | |||||||||||||
Woodgate [109] | 2002 | As | Te | Ge | Sb | Al | 5 | ||||||||||||||
Wright & Welbourn [110] | 2002 | As | Te | Ge | Si | B | 5 | ||||||||||||||
e-encyclopedia [111] | 2003 | As | Te | Ge | Si | Sb | B | Se | 7 | ||||||||||||
Gupta [112] | 2003 | As | Te | Ge | Si | Sb | B | 6 | |||||||||||||
Hunt [113] | 2003 | As | Te | Ge | Si | Sb | B | 6 | |||||||||||||
Myers [114] | 2003 | As | Te | Ge | Si | Sb | B | At | Se | 8 | |||||||||||
Williams [115] | 2003 | As | Te | Ge | Si | Sb | B | Po | 7 | ||||||||||||
Atkins [116] | 2004 | As | Te | Ge | Si | Sb | B | Po | 7 | ||||||||||||
Cox [117] | 2004 | As | Te | Ge | Si | Sb | Se | 6 | |||||||||||||
Gilbert, Kirss & Davies [118] | 2004 | As | Te | Ge | Si | Sb | B | At | Se | 8 | |||||||||||
Reilly [119] | 2004 | As | Te | Ge | Si | Sb | B | Po | At | Se | 9 | ||||||||||
Ebbing & Gammon [120] | 2005 | As | Te | Ge | Si | Sb | B | At | 7 | ||||||||||||
Fry & Page [121] | 2005 | As | Te | Ge | Si | Sb | B | 6 | |||||||||||||
Halliday, Resnick & Walker [122] | 2005 | As | Te | Ge | Si | Sb | B | Po | At | 8 | |||||||||||
Holler & Selegue [123] | 2005 | As | Te | Ge | Si | Sb | B | Po | (At) | 7.5 | |||||||||||
Kotz, Treichel & Weaver [124] | 2005 | As | Te | Ge | Si | Sb | B | 6 | |||||||||||||
Meyer [125] | 2005 | As | Te | Ge | Si | Sb | B | At | 7 | ||||||||||||
Orchin [126] | 2005 | As | Te | Ge | Si | Sb | B | Po | At | 8 | |||||||||||
Swenson [127] | 2005 | As | Te | Ge | Si | Sb | B | Po | At | Se | C | Bi | 11 | ||||||||
Baird [128] | 2006 | As | Te | Ge | Si | Sb | B | At | 7 | ||||||||||||
Blei & Odian [129] | 2006 | As | Te | Ge | Si | Sb | Po | At | Lv | 8 | |||||||||||
Brown & Holme [130] | 2006 | As | Te | Ge | Si | Sb | B | At | 7 | ||||||||||||
Dashek & Harrison [131] | 2006 | As | Te | Ge | Si | Sb | B | Po | At | 8 | |||||||||||
Finch et al. [132] | 2006 | As | Te | Ge | Si | Sb | B | Se | 7 | ||||||||||||
Goldfrank & Flomenbaum [133] | 2006 | As | Te | Ge | Si | Sb | B | At | 7 | ||||||||||||
Hatt [134] | 2006 | As | Te | Ge | Si | Sb | B | Se | 7 | ||||||||||||
Hérold [135] | 2006 | As | Ge | Si | B | Po | (At) | Se | C | Bi | P | 9.5 | |||||||||
McMonagle [136] | 2006 | As | Te | Ge | Si | B | Lv | Fl Mc | 8 | ||||||||||||
Rayner-Canham & Overton [137] | 2006 | As | Te | Ge | Si | B | 5 | ||||||||||||||
Silberberg [138] | 2006 | As | Te | Ge | Si | Sb | B | 6 | |||||||||||||
Slade [139] | 2006 | As | Te | Ge | Si | Sb | B | Po | 7 | ||||||||||||
Wertheim, Oxlade & Stockley [140] | 2006 | As | Te | Ge | Si | Sb | B | At | Se | 8 | |||||||||||
Whitley [141] | 2006 | As | Te | Ge | Si | Sb | B | Po | 7 | ||||||||||||
American Chemical Society [142] | 2007 | As | Te | Ge | Si | Sb | B | Po | 7 | ||||||||||||
Astruc [143] | 2007 | As | Si | B | Se | P | S | 6 | |||||||||||||
Casper [144] | 2007 | As | Te | Ge | Si | Sb | B | Po | 7 | ||||||||||||
Crystal [145] | 2007 | As | Te | Ge | Si | Sb | B | Po | 7 | ||||||||||||
DeGraff [146] | 2007 | As | Te | Ge | Si | Sb | B | Po | 7 | ||||||||||||
Joesten, Hogg & Castellion [147] | 2007 | As | Te | Ge | Si | Sb | B | 6 | |||||||||||||
Lewis [148] | 2007 | As | Te | Ge | Si | Sb | B | Po | Se | C | P | S | 11 | ||||||||
Petty [149] | 2007 | As | Te | Ge | Si | Sb | B | Po | At | Se | C | Bi | P | Sn | 13 | ||||||
Rösler, Harders & Bäker [150] | 2007 | As | Te | Ge | Si | Sb | B | (Sn) | 6.5 | ||||||||||||
Saunders [151] | 2007 | As | Te | Ge | Si | Sb | B | Po | At | 8 | |||||||||||
Saunders [152] | 2007 | As | Te | Ge | Si | Sb | B | Po | At | 8 | |||||||||||
Shipman, Wilson & Tood [153] | 2007 | As | Te | Ge | Si | Sb | B | 6 | |||||||||||||
Bauer, Birk & Sawyer [154] | 2008 | As | Te | Ge | Si | Sb | B | At | 7 | ||||||||||||
Clugston & Flemming [155] | 2008 | As | Te | Ge | Si | Sb | Se | 6 | |||||||||||||
Encyclopedia Columbia [156] | 2008 | As | Te | Sb | Se | 4 | |||||||||||||||
Ham [157] | 2008 | As | Te | Ge | Si | Sb | B | Po | 7 | ||||||||||||
Kelter, Mosher & Scott [158] | 2008 | As | Te | Ge | Si | Sb | B | At | 7 | ||||||||||||
Masterton & Hurley [159] | 2008 | As | Te | Ge | Si | Sb | B | 6 | |||||||||||||
Merck [160] | 2008 | As | Te | Ge | Si | Sb | B | Po | 7 | ||||||||||||
Nicolaou & Montagnon [161] | 2008 | As | Te | Ge | Si | Sb | B | Po | At | C | 9 | ||||||||||
Řezanka & Sigler [162] | 2008 | As | Te | Si | B | At | Se | 6 | |||||||||||||
Tro & Neu [163] | 2008 | As | Te | Ge | Si | Sb | B | 6 | |||||||||||||
Vallero [164] | 2008 | As | Te | Ge | Si | Sb | B | Po | 7 | ||||||||||||
Brown et al. [165] | 2009 | As | Te | Ge | Si | Sb | B | 6 | |||||||||||||
Burrows et al. [166] | 2009 | As | Te | Ge | Si | Sb | B | Se | 7 | ||||||||||||
Castor-Perry [167] | 2009 | As | Te | Ge | Si | Sb | B | Po | At | I | 9 | ||||||||||
Cracolice & Peters [168] | 2009 | As | Te | Ge | Si | Sb | B | At | 7 | ||||||||||||
Economou [169] | 2009 | As | Te | Ge | Si | Sb | B | Po | At | Al | 9 | ||||||||||
Habashi [170] | 2009 | As | Te | Ge | Si | Sb | B | Po | Se | Bi | 9 | ||||||||||
Hein & Arena [171] | 2009 | As | Te | Ge | Si | Sb | B | Po | 7 | ||||||||||||
Leach [172] | 2009 | As | Te | Ge | Si | Sb | B | Po | 7 | ||||||||||||
Manning [173] | 2009 | As | Te | Ge | Si | Sb | B | Po | 7 | ||||||||||||
McMurray & Fay [174] | 2009 | As | Te | Ge | Si | Sb | B | At | 7 | ||||||||||||
Reger, Goode & Ball [175] | 2009 | As | Te | Ge | Si | Sb | B | 6 | |||||||||||||
Schnepp [176] | 2009 | As | Te | Ge | Si | Sb | B | Po | At | 8 | |||||||||||
Shubert & Leyba [177] | 2009 | As | Te | Ge | Si | Sb | B | 6 | |||||||||||||
Whitten et al. [178] | 2009 | As | Te | Ge | Si | Sb | B | At | 7 | ||||||||||||
Aldinger & Weberruss [179] | 2010 | As | Te | Ge | Si | Sb | B | 6 | |||||||||||||
Banks et al. [180] | 2010 | As | Te | Ge | Si | Sb | B | 6 | |||||||||||||
Fayer [181] | 2010 | As | Te | Ge | Si | Sb | B | Po | At | 8 | |||||||||||
Gray [182] | 2010 | As | Te | Ge | Si | Sb | B | Po | 7 | ||||||||||||
Groysman [183] | 2010 | As | Te | Ge | Si | Sb | Po | 6 | |||||||||||||
Halka & Nordstrom [184] | 2010 | As | Te | Ge | Si | Sb | B | Po | 7 | ||||||||||||
Lombi E & Holm PE [185] | 2010 | As | Te | Ge | Si | Sb | B | Po | At | 8 | |||||||||||
NEST Association [186] | 2010 | As | Te | Ge | Si | Sb | B | At | 7 | ||||||||||||
RCCS [187] | 2010 | As | Te | Ge | Si | Sb | B | Po | At | Se | C | Bi | P | Sn | 13 | ||||||
Senese [188] | 2010 | As | Te | Ge | Si | Sb | (B) | Po | At | (Se) | C | 9 | |||||||||
Weiner [189] | 2010 | As | Te | Ge | Si | Sb | B | Po | 7 | ||||||||||||
Barbalace [190] | 2011 | As | Te | Ge | Si | Sb | B | Po | 7 | ||||||||||||
Encyclopædia Britannica Online [191] | 2011 | As | Te | Ge | Si | Sb | B | (Po) | (At) | 7 | |||||||||||
Helmenstine [192] | 2011 | As | Te | Ge | Si | Sb | B | (Po) | 6.5 | ||||||||||||
Moore [193] | 2011 | As | Te | Ge | Si | Sb | B | At | 7 | ||||||||||||
QA International [194] | 2011 | As | Te | Ge | Si | Sb | B | Se | 7 | ||||||||||||
Element | Arsenic | Tellurium | Germanium | Silicon | Antimony | Boron | Polonium | Astatine | Selenium | Aluminium | Carbon | Bismuth | Phosphorus | Beryllium | Tin | Sulfur | Livermorium | Iodine | Other |
There is an average of 7.15 elements per metalloid list.
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.
The resulting geometric trend line has the formula y = 199.47e−0.7423x and an R2 value of 0.9962. [n 3]
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).
Astatine is a chemical element; it has symbol At and atomic number 85. It is the rarest naturally occurring element in the Earth's crust, occurring only as the decay product of various heavier elements. All of astatine's isotopes are short-lived; the most stable is astatine-210, with a half-life of 8.1 hours. Consequently, a solid sample of the element has never been seen, because any macroscopic specimen would be immediately vaporized by the heat of its radioactivity.
The periodic table, also known as the periodic table of the elements, is an ordered arrangement of the chemical elements into rows ("periods") and columns ("groups"). It is an icon of chemistry and is widely used in physics and other sciences. It is a depiction of the periodic law, which states that when the elements are arranged in order of their atomic numbers an approximate recurrence of their properties is evident. The table is divided into four roughly rectangular areas called blocks. Elements in the same group tend to show similar chemical characteristics.
In chemistry, a transition metal is a chemical element in the d-block of the periodic table, though the elements of group 12 are sometimes excluded. The lanthanide and actinide elements are called inner transition metals and are sometimes considered to be transition metals as well.
The data below tabulates standard electrode potentials (E°), in volts relative to the standard hydrogen electrode, at:
A metalloid is a type of chemical element which has a preponderance of properties in between, or that are a mixture of, those of metals and nonmetals. There is no standard definition of a metalloid and no complete agreement on which elements are metalloids. Despite the lack of specificity, the term remains in use in the literature of chemistry. Metalloids typically have a metallic appearance but are brittle and not as malleable as metals.
Nonmetals in chemistry or non-metallic elements are chemical elements that have high electronegativity and mostly lack distinctive metallic properties. They range from colorless gases like hydrogen to shiny crystals like iodine. Physically, they are usually lighter than metals and are often poor conductors of heat and electricity. Since nonmetals have high electronegativity they usually attract electrons in a chemical bond with another element, and their oxides tend to be acidic.
A noble metal is ordinarily regarded as a metallic chemical element that is generally resistant to corrosion and is usually found in nature in its raw form. Gold, platinum, and the other platinum group metals are most often so classified. Silver, copper, and mercury are sometimes included as noble metals, but each of these usually occurs in nature combined with sulfur.
A period 3 element is one of the chemical elements in the third row of the periodic table of the chemical elements. The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behavior of the elements as their atomic number increases: a new row is begun when chemical behavior begins to repeat, meaning that elements with similar behavior fall into the same vertical columns. The third period contains eight elements: sodium, magnesium, aluminium, silicon, phosphorus, sulfur, chlorine and argon. The first two, sodium and magnesium, are members of the s-block of the periodic table, while the others are members of the p-block. All of the period 3 elements occur in nature and have at least one stable isotope.
In chemistry, an interhalogen compound is a molecule which contains two or more different halogen atoms and no atoms of elements from any other group.
Since Dimitri Mendeleev formulated the periodic law in 1871, and published an associated periodic table of chemical elements, authors have experimented with varying types of periodic tables including for teaching, aesthetic or philosophical purposes.
There are currently 118 known chemical elements with a wide range of physical and chemical properties. Amongst this diversity, scientists have found it useful to apply names for various sets of elements that have similar properties, to varying degrees. Many of these sets are formally recognized by the standards body IUPAC.
A block of the periodic table is a set of elements unified by the atomic orbitals their valence electrons or vacancies lie in. The term seems to have been first used by Charles Janet. Each block is named after its characteristic orbital: s-block, p-block, d-block, f-block and g-block.
The origin and usage of the term metalloid is convoluted. Its origin lies in attempts, dating from antiquity, to describe metals and to distinguish between typical and less typical forms. It was first applied to metals that floated on water, and then more popularly to nonmetals. Only recently, since the mid-20th century, has it been widely used to refer to elements with intermediate or borderline properties between metals and nonmetals.
The chemical elements can be broadly divided into metals, metalloids, and nonmetals according to their shared physical and chemical properties. All metals have a shiny appearance ; are good conductors of heat and electricity; form alloys with other metals; and have at least one basic oxide. Metalloids are metallic-looking brittle solids that are either semiconductors or exist in semiconducting forms, and have amphoteric or weakly acidic oxides. Typical nonmetals have a dull, coloured or colourless appearance; are brittle when solid; are poor conductors of heat and electricity; and have acidic oxides. Most or some elements in each category share a range of other properties; a few elements have properties that are either anomalous given their category, or otherwise extraordinary.
The dividing line between metals and nonmetals can be found, in varying configurations, on some representations of the periodic table of the elements. Elements to the lower left of the line generally display increasing metallic behaviour; elements to the upper right display increasing nonmetallic behaviour. When presented as a regular stair-step, elements with the highest critical temperature for their groups lie just below the line.
The metallic elements in the periodic table located between the transition metals to their left and the chemically weak nonmetallic metalloids to their right have received many names in the literature, such as post-transition metals, poor metals, other metals, p-block metals and chemically weak metals. The most common name, post-transition metals, is generally used in this article.
Heavy metals are generally defined as metals with relatively high densities, atomic weights, or atomic numbers. The criteria used, and whether metalloids are included, vary depending on the author and context. In metallurgy, for example, a heavy metal may be defined on the basis of density, whereas in physics the distinguishing criterion might be atomic number, while a chemist would likely be more concerned with chemical behaviour. More specific definitions have been published, none of which have been widely accepted. The definitions surveyed in this article encompass up to 96 out of the 118 known chemical elements; only mercury, lead and bismuth meet all of them. Despite this lack of agreement, the term is widely used in science. A density of more than 5 g/cm3 is sometimes quoted as a commonly used criterion and is used in the body of this article.