Massey AG 2000, Main Group Chemistry, 2nd ed., John Wiley & Sons, Chichester, ISBN 978-0-471-49039-5 There is no precise definition of a nonmetal; [6] any list of such is open to debate and revision. [7] Which elements are included depends on the properties regarded as most representative of nonmetallic or metallic character. [n 3] Hanley JJ & Koga KT 2018, "Halogens in terrestrial and cosmic geochemical systems: Abundances, geochemical behaviours, and analytical methods" in The Role of Halogens in Terrestrial and Extraterrestrial Geochemical Processes: Surface, Crust, and Mantle, Harlov DE & Aranovich L (eds.), Springer, Cham, ISBN 978-3-319-61667-4

Bohlmann R 1992, "Synthesis of halides", in Winterfeldt E (ed.), Heteroatom manipulation, Pergamon Press, Oxford, ISBN 978-0-08-091249-3 Malone LJ & Dolter T 2008, Basic Concepts of Chemistry, 8th ed., John Wiley & Sons, Hoboken, ISBN 978-0-471-74154-1 Kugler HK & Keller C (eds) 1985, Gmelin Handbook of Inorganic and Organometallic chemistry, 8th ed., "At, Astatine", system no. 8a, Springer-Verlag, Berlin, ISBN 3-540-93516-9 Phillips JC 1973, "The chemical structure of solids", in Hannay NB (ed.), Treatise on Solid State Chemistry, vol. 1, Plenum Press, New York, pp.1–42, ISBN 978-1-4684-2663-2 Florez et al. 2022, "From the gas phase to the solid state: The chemical bonding in the superheavy element flerovium", The Journal of Chemical Physics, vol. 157, 064304, doi: 10.1063/5.0097642

What are Metals?

Nonmetals tend to have low density and high electronegativity (the ability of an atom in a molecule to attract electrons to itself). They range from colorless gases like hydrogen to shiny solids like the graphite form of carbon. Nonmetals are often poor conductors of heat and electricity, and when solid tend to be brittle or crumbly. In contrast, metals are good conductors and most are pliable. While oxides of metals tend to be basic, those of nonmetals tend to be acidic. Jenkins GM & Kawamura K 1976, Polymeric Carbons—Carbon Fibre, Glass and Char, Cambridge University Press, Cambridge, ISBN 978-0-521-20693-8 While certain elements have traditionally been classified as nonmetals and others as metals, some overlapping of properties occurs. Writing early in the twentieth century, by which time the era of modern chemistry had been well-established, [97] Humphrey [98] observed that: Iodine is sufficiently corrosive to cause lesions resembling thermal burns, if handled without suitable protection, [108] and tincture of iodine will smoothly dissolve Au. [109] That said, while "F, Cl and Br will all oxidize Fe 2+ (aq) to Fe 3+(aq) ... iodine ... is such a [relatively] weak oxidizing agent that it cannot remove electrons from Fe(II) ions to form Fe(III) ions." [110] Thus, for the reaction X 2 + 2e − → 2X −(aq) the reduction potentials are F +2.87 V; Cl +1.36; Br +1.09; I +0.54. Here Fe 3+ + e − → Fe 3+ +0.77. [111] Thus F 2, Cl 2 and Br 2 will oxidize Fe 2+ to Fe 3+ but Fe 3+ will oxidize I − to I 2. Iodine has previously been referred to as a moderately strong oxidizing agent. [112]

Edwards PP & Sienko MJ 1983, "On the occurrence of metallic character in the periodic table of the elements", Journal of Chemical Education, vol. 60, no. 9, doi: 10.1021/ed060p691, PMID 25666074 Holderness A & Berry M 1979, Advanced Level Inorganic Chemistry, 3rd ed., Heinemann Educational Books, London, ISBN 978-0-435-65435-1Solid iodine has a silvery metallic appearance under white light at room temperature. [21] It sublimes at ordinary and higher temperatures, passing from solid to gas; its vapours are violet-colored. [22]

Jensen WB 1986, Classification, symmetry and the periodic table, Computers & Mathematics with Applications, vol. 12B, nos. 1/2, pp. 487−510, doi: 10.1016/0898-1221(86)90167-7 Faraday M 1853, The Subject Matter of a Course of Six Lectures on the Non-metallic Elements, (arranged by John Scoffern), Longman, Brown, Green, and Longmans, London Chemical behavior—Nonmetal oxides tend to be acidic, providing another useful criterion for identifying nonmetals. Atkins PA 2001, The Periodic Kingdom: A Journey Into the Land of the Chemical Elements, Phoenix, London, ISBN 978-1-85799-449-0 Messler Jr RW 2011, The Essence of Materials for Engineers, Jones and Bartlett Learning, Sudbury, Massachusetts, ISBN 978-0-7637-7833-0Burke RA 2020, Hazmatology: The Science of Hazardous Materials, Vol. 3: Applied Chemistry and Physics, CRC Press, Boca Raton, ISBN 978-1-138-31652-2 a set of unclassified nonmetals, encompassing elements like hydrogen, carbon, nitrogen, and oxygen, for which there is no widely recognized collective name; [n 19] and

The classification of nonmetals can vary, with approaches ranging from as few as two types to as many as six or seven. For instance, the periodic table in the Encyclopaedia Britannica recognizes noble gases, halogens, and other nonmetals, and splits the elements commonly recognized as metalloids between "other metals" and "other nonmetals". [113] On the other hand, on the Royal Society of Chemistry periodic table includes both nonmetals and metals (or nonmetals only) in seven of twelve color categories and shows metalloids in both its metal and nonmetal lists. [114] [n 17] The single dagger nonmetals N, S and iodine are somewhat hobbled as to the strength of their nonmetallic character: Main article: Discovery of the nonmetals The Alchemist Discovering Phosphorus (1771) by Joseph Wright. The alchemist is Hennig Brand; the glow emanates from the combustion of phosphorus inside the flask. Jones takes a philosophical or pragmatic view to these questions. He writes: "Though classification is an essential feature of all branches of science, there are always hard cases at the boundaries. The boundary of a class is rarely sharp ... Scientists should not lose sleep over the hard cases. As long as a classification system is beneficial to economy of description, to structuring knowledge and to our understanding, and hard cases constitute a small minority, then keep it. If the system becomes less than useful, then scrap it and replace it with a system based on different shared characteristics". [129]The metalloids are commonly found combined with oxygen, sulfur, or, in the case of tellurium, gold or silver. [157] Boron is typically found in boron-oxygen borate minerals, including in volcanic spring waters. Silicon is present in the silicon-oxygen mineral silica (sand). Germanium, arsenic, and antimony are mainly found as components of sulfide ores. Tellurium is often found in telluride minerals of gold or silver. In some instances, native forms of arsenic, antimony, and tellurium have been reported. [158] Unclassified nonmetals [ edit ]