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 (at least when freshly polished); 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.
Metals appear lustrous (beneath any patina); form mixtures (alloys) when combined with other metals; tend to lose or share electrons when they react with other substances; and each forms at least one predominantly basic oxide.
Some metals appear coloured (Cu, Cs, Au), have low densities (e.g. Be, Al) or very high melting points, are liquids at or near room temperature, are brittle (e.g. Os, Bi), not easily machined (e.g. Ti, Re), or are noble (hard to oxidise) or have nonmetallic structures (Mn and Ga are structurally analogous to, respectively, white P and I).
(Metalloids are metallic looking brittle solids; tend to share electrons when they react with other substances; have weakly acidic or amphoteric oxides; and are usually found naturally in combined states.
Most are semiconductors, and moderate thermal conductors, and have structures that are more open than those of most metals.
Some metalloids (As, Sb) conduct electricity like metals.
The metalloids, as the smallest major category of elements, are not subdivided further).
25 ml of bromine, a dark red-brown liquid at room temperature
Nonmetals have open structures (unless solidified from gaseous or liquid forms); tend to gain or share electrons when they react with other substances; and do not form distinctly basic oxides.
Most are gases at room temperature; have relatively low densities; are poor electrical and thermal conductors; have relatively high ionisation energies and electronegativities; form acidic oxides; and are found naturally in uncombined states in large amounts.
Some nonmetals (C, black P, S and Se) are brittle solids at room temperature (although each of these also have malleable, pliable or ductile allotropes).
From left to right in the periodic table, the nonmetals can be subdivided into the reactive nonmetals which, being nearest to the metalloids, show some incipient metallic character, and the monatomic noble gases, which are almost completely inert.
Comparison of properties
Number of metalloid properties that resemble metals or nonmetals
The characteristic properties of metals and nonmetals are quite distinct, as shown in the table below. Metalloids, straddling the metal-nonmetal border, are mostly distinct from either, but in a few properties resemble one or the other, as shown in the shading of the metalloid column below and summarized in the small table at the top of this section.
Authors differ in where they divide metals from nonmetals and in whether they recognize an intermediate metalloid category. Some authors count metalloids as nonmetals with weakly nonmetallic properties.[n 1] Others count some of the metalloids as post-transition metals.[n 2]
The common notions that "alkali metal ions (group 1A) always have a +1 charge" and that "transition elements do not form anions" are textbook errors. The synthesis of a crystalline salt of the sodium anion Na− was reported in 1974. Since then further compounds ("alkalides") containing anions of all other alkali metals except Li and Fr, as well as that of Ba, have been prepared. In 1943, Sommer reported the preparation of the yellow transparent compound CsAu. This was subsequently shown to consist of caesium cations (Cs+) and auride anions (Au−) although it was some years before this conclusion was accepted. Several other aurides (KAu, RbAu) have since been synthesized, as well as the red transparent compound Cs2Pt which was found to contain Cs+ and Pt2− ions.
Well-behaved metals have crystal structures featuring unit cells with up to four atoms. Manganese has a complex crystal structure with a 58-atom unit cell, effectively four different atomic radii, and four different coordination numbers (10, 11, 12 and 16). It has been described as resembling "a quaternary intermetallic compound with four Mn atom types bonding as if they were different elements." The half-filled 3d shell of manganese appears to be the cause of the complexity. This confers a large magnetic moment on each atom. Below 727 °C, a unit cell of 58 spatially diverse atoms represents the energetically lowest way of achieving a zero net magnetic moment. The crystal structure of manganese makes it a hard and brittle metal, with low electrical and thermal conductivity. At higher temperatures "greater lattice vibrations nullify magnetic effects" and manganese adopts less complex structures.
The only elements strongly attracted to magnets are iron, cobalt, and nickel at room temperature, gadolinium just below, and terbium, dysprosium, holmium, erbium, and thulium at ultra cold temperatures (below −54 °C, −185 °C, −254 °C, −254 °C, and −241 °C respectively).
The malleability of gold is extraordinary: a fist sized lump can be hammered and separated into one million paper back sized sheets, each 10 nm thick, 1600 times thinner than regular kitchen aluminium foil (0.016 mm thick).
Bricks and bowling balls will float on the surface of mercury thanks to it having a density 13.5 times that of water. Equally, a solid mercury bowling ball would weigh around 50 pounds and, if it could be kept cold enough, would float on the surface of liquid gold.
The only metal having an ionisation energy higher than some nonmetals (sulfur and selenium) is mercury.
Mercury and its compounds have a reputation for toxicity but on a scale of 1 to 10, dimethylmercury ((CH3)2Hg) (abbr. DMM), a volatile colourless liquid, has been described as a 15. It is so dangerous that scientists have been encouraged to use less toxic mercury compounds wherever possible. In 1997, Karen Wetterhahn, a professor of chemistry specialising in toxic metal exposure, died of mercury poisoning ten months after a few drops of DMM landed on her "protective" latex gloves. Although Wetterhahn had been following the then published procedures for handling this compound, it passed through her gloves and skin within seconds. It is now known that DMM is exceptionally permeable to (ordinary) gloves, skin and tissues. And its toxicity is such that less than one-tenth of a ml applied to the skin will be seriously toxic.
The expression, to "go down like a lead balloon" is anchored in the common view of lead as a dense, heavy metal—being nearly as dense as mercury. However, it is possible to construct a balloon made of lead foil, filled with a helium and air mixture, which will float and be buoyant enough to carry a small load.
The only element with a naturally occurring isotope capable of undergoing nuclear fission is uranium. The capacity of uranium-235 to undergo fission was first suggested (and ignored) in 1934, and subsequently discovered in 1938.[n 28]
It is a commonly held belief that metals reduce their electrical conductivity when heated. Plutonium increases its electrical conductivity when heated in the temperature range of around –175 to +125 °C.
The thermal conductivity of silicon is better than that of most metals.
A sponge-like porous form of silicon (p-Si) is typically prepared by the electrochemical etching of silicon wafers in a hydrofluoric acid solution. Flakes of p-Si sometimes appear red; it has a band gap of 1.97–2.1 eV. The many tiny pores in porous silicon give it an enormous internal surface area, up to 1,000 m2/cm3. When exposed to an oxidant, especially a liquid oxidant, the high surface-area to volume ratio of p-Si creates a very efficient burn, accompanied by nano-explosions, and sometimes by ball-lightning-like plasmoids with, for example, a diameter of 0.1–0.8 m, a velocity of up to 0.5 m/s and a lifetime of up to 1s. The first ever spectrographic analysis of a ball lightning event (in 2012) revealed the presence of silicon, iron and calcium, these elements also being present in the soil.
A high-energy explosive form of antimony was first obtained in 1858. It is prepared by the electrolysis of any of the heavier antimony trihalides (SbCl3, SbBr3, SbI3) in a hydrochloric acid solution at low temperature. It comprises amorphous antimony with some occluded antimony trihalide (7–20% in the case of the trichloride). When scratched, struck, powdered or heated quickly to 200 °C, it "flares up, emits sparks and is converted explosively into the lower-energy, crystalline grey antimony."
Less well known of the oxides of hydrogen is the trioxide, H2O3. Berthelot proposed the existence of this oxide in 1880 but his suggestion was soon forgotten as there was no way of testing it using the technology of the time. Hydrogen trioxide was prepared in 1994 by replacing the oxygen used in the industrial process for making hydrogen peroxide, with ozone. The yield is about 40 per cent, at –78 °C; above around –40 °C it decomposes into water and oxygen. Derivatives of hydrogen trioxide, such as F3C–O–O–O–CF3 ("bis(trifluoromethyl) trioxide") are known; these are metastable at room temperature.Mendeleev went a step further, in 1895, and proposed the existence of hydrogen tetroxideHO–O–O–OH as a transient intermediate in the decomposition of hydrogen peroxide; this was prepared and characterised in 1974, using a matrix isolation technique. Alkali metalozonide salts of the unknown hydrogen ozonide (HO3) are also known; these have the formula MO3.
At temperatures below 0.3 and 0.8 K respectively, helium-3 and helium-4 each have a negative enthalpy of fusion. This means that, at the appropriate constant pressures, these substances freeze with the addition of heat.
Until 1999 helium was thought to be too small to form a cage clathrate—a compound in which a guest atom or molecule is encapsulated in a cage formed by a host molecule—at atmospheric pressure. In that year the synthesis of microgram quantities of He@C20H20 represented the first such helium clathrate and (what was described as) the world's smallest helium balloon.
Graphite is the most electrically conductive nonmetal, better than some metals.
Diamond is the best natural conductor of heat; it even feels cold to the touch. Its thermal conductivity (2,200 W/m•K) is five times greater than the most conductive metal (Ag at 429); 300 times higher than the least conductive metal (Pu at 6.74); and nearly 4,000 times that of water (0.58) and 100,000 times that of air (0.0224). This high thermal conductivity is used by jewelers and gemologists to separate diamonds from imitations.
Graphene aerogel, produced in 2012 by freeze-drying a solution of carbon nanotubes and graphite oxide sheets and chemically removing oxygen, is seven times lighter than air, and ten per cent lighter than helium. It is the lightest solid known (0.16 mg/cm3), conductive and elastic.
The least stable and most reactive form of phosphorus is the whiteallotrope. It is a hazardous, highly flammable and toxic substance, spontaneously igniting in air and producing phosphoric acid residue. It is therefore normally stored under water. White phosphorus is also the most common, industrially important, and easily reproducible allotrope, and for these reasons is regarded as the standard state of phosphorus. The most stable form is the black allotrope, which is a metallic looking, brittle and relatively non-reactive semiconductor (unlike the white allotrope, which has a white or yellowish appearance, is pliable, highly reactive and a semiconductor). When assessing periodicity in the physical properties of the elements it needs to be borne in mind that the quoted properties of phosphorus tend to be those of its least stable form rather than, as is the case with all other elements, the most stable form.
The mildest of the halogens, iodine is the active ingredient in tincture of iodine, a disinfectant. This can be found in household medicine cabinets or emergency survival kits. Tincture of iodine will rapidly dissolve gold, a task ordinarily requiring the use of aqua regia (a highly corrosive mixture of nitric and hydrochloric acids).
Eby et al. discuss the weak chemical behaviour of the elements close to the metal-nonmetal borderline.
Booth and Bloom say "A period represents a stepwise change from elements strongly metallic to weakly metallic to weakly nonmetallic to strongly nonmetallic, and then, at the end, to an abrupt cessation of almost all chemical properties ...".
Cox notes "nonmetallic elements close to the metallic borderline (Si, Ge, As, Sb, Se, Te) show less tendency to anionic behaviour and are sometimes called metalloids."
^See, for example, Huheey, Keiter & Keiter who classify Ge and Sb as post-transition metals.
^At standard pressure and temperature, for the elements in their most thermodynamically stable forms, unless otherwise noted
^Copernicium is reported to be the only metal known to be a gas at room temperature.
^For polycrystalline forms of the elements unless otherwise noted. Determining Poisson's ratio accurately is a difficult proposition and there could be considerable uncertainty in some reported values.
^Beryllium has the lowest known value (0.0476) amongst elemental metals; indium and thallium each have the highest known value (0.46). Around one third show a value ≥ 0.33.
^The Goldhammer-Herzfeld criterion is a ratio that compares the force holding an individual atom's valence electrons in place with the forces, acting on the same electrons, arising from interactions between the atoms in the solid or liquid element. When the interatomic forces are greater than or equal to the atomic force, valence electron itinerancy is indicated. Metallic behaviour is then predicted. Otherwise nonmetallic behaviour is anticipated. The Goldhammer-Herzfeld criterion is based on classical arguments. It nevertheless offers a relatively simple first order rationalization for the occurrence of metallic character amongst the elements.
^Metals have electrical conductivity values of from 6.9 × 103 S•cm−1 for manganese to 6.3 × 105 for silver.
^Metalloids have electrical conductivity values of from 1.5 × 10−6 S•cm−1 for boron to 3.9 × 104 for arsenic. If selenium is included as a metalloid the applicable conductivity range would start from ~10−9 to 10−12 S•cm−1.
^Nonmetals have electrical conductivity values of from ~10−18 S•cm−1 for the elemental gases to 3 × 104 in graphite.
^Mott and Davis note however that 'liquid europium has a negative temperature coefficient of resistance' i.e. that conductivity increases with rising temperature
^Sulfates of osmium have not been characterized with any great degree of certainty.
^Common metalloids: Boron is reported to be capable of forming an oxysulfate (BO)2SO4, a bisulfate B(HSO4)3 and a sulfate B2(SO4)3. The existence of a sulfate has been disputed. In light of the existence of silicon phosphate, a silicon sulfate might also exist. Germanium forms an unstable sulfate Ge(SO4)2 (d 200 °C). Arsenic forms oxide sulfates As2O(SO4)2 (= As2O3.2SO3) and As2(SO4)3 (= As2O3.3SO3). Antimony forms a sulfate Sb2(SO4)3 and an oxysulfate (SbO)2SO4. Tellurium forms an oxide sulfate Te2O3(SO)4.Less common: Polonium forms a sulfate Po(SO4)2. It has been suggested that the astatine cation forms a weak complex with sulfate ions in acidic solutions.
^Hydrogen forms hydrogen sulfate H2SO4. Carbon forms (a blue) graphite hydrogen sulfate C+ 24HSO– 4 • 2.4H2SO4. Nitrogen forms nitrosyl hydrogen sulfate (NO)HSO4 and nitronium (or nitryl) hydrogen sulfate (NO2)HSO4. There are indications of a basic sulfate of selenium SeO2.SO3 or SeO(SO4). Iodine forms a polymeric yellow sulfate (IO)2SO4.
^Based on a table of the elemental composition of the biosphere, and lithosphere (crust, atmosphere, and seawater) in Georgievskii, and the masses of the crust and hydrosphere give in Lide and Frederikse. The mass of the biosphere is negligible, having a mass of about one billionth that of the lithosphere. "The oceans constitute about 98 percent of the hydrosphere, and thus the average composition of the hydrosphere is, for all practical purposes, that of seawater."
^Hydrogen gas is produced by some bacteria and algae and is a natural component of flatus. It can be found in the Earth's atmosphere at a concentration of 1 part per million by volume.
^Fluorine can be found in its elemental form, as an occlusion in the mineral antozonite
^ In 1934, a team led by Enrico Fermi postulated that transuranic elements may have been produced as a result of bombarding uranium with neutrons, a finding which was widely accepted for a few years. In the same year Ida Noddack, a German scientist and subsequently a three-time Nobel prize nominee, criticised this assumption, writing "It is conceivable that the nucleus breaks up into several large fragments, which would of course be isotopes of known elements but would not be neighbors of the irradiated element."[emphasis added] In this, Noddak defied the understanding of the time without offering experimental proof or theoretical basis, but nevertheless presaged what would be known a few years later as nuclear fission. Her paper was generally ignored as, in 1925, she and two colleagues claimed to have discovered element 43, then proposed to be called masurium (later discovered in 1936 by Perrier and Segrè, and named technetium). Had Ida Noddack's paper been accepted it is likely that Germany would have had an atomic bomb and, 'the history of the world would have been [very] different.'
^Jauncey 1948, p. 500: 'Nonmetals mostly have negative temperature coefficients. For instance, carbon ... [has a] resistance [that] decreases with a rise in temperature. However, recent experiments on very pure graphite, which is a form of carbon, have shown that pure carbon in this form behaves similarly to metals in regard to its resistance.'
Appalakondaiah S, Vaitheeswaran G, Lebègue S, Christensen NE & Svane A 2012, 'Effect of van der Waals interactions on the structural and elastic properties of black phosphorus,' Physical Review B, vol. 86, pp. 035105‒1 to 9, doi:10.1103/PhysRevB.86.035105
Askeland DR, Fulay PP & Wright JW 2011, The science and engineering of materials, 6th ed., Cengage Learning, Stamford, CT, ISBN 0-495-66802-8
Atkins P, Overton T, Rourke J, Weller M & Armstrong F 2006, Shriver & Atkins' inorganic chemistry, 4th ed., Oxford University Press, Oxford, ISBN 0-7167-4878-9
Austen K 2012, 'A factory for elements that barely exist', NewScientist, 21 Apr, p. 12, ISSN 1032-1233
Bagnall KW 1966, The chemistry of selenium, tellurium and polonium, Elsevier, Amsterdam
Bailar JC, Moeller T, Kleinberg J, Guss CO, Castellion ME & Metz C 1989, Chemistry, 3rd ed., Harcourt Brace Jovanovich, San Diego, ISBN 0-15-506456-8
Bassett LG, Bunce SC, Carter AE, Clark HM & Hollinger HB 1966, Principles of chemistry, Prentice-Hall, Englewood Cliffs, NJ
Batsanov SS & Batsanov AS 2012, Introduction to structural chemistry, Springer Science+Business Media, Dordrecht, ISBN 978-94-007-4770-8
Benedict M, Alvarez LW, Bliss LA, English SG, Kinzell AB, Morrison P, English FH, Starr C & Williams WJ 1946, 'Technological control of atomic energy activities', "Bulletin of the Atomic Scientists," vol. 2, no. 11, pp. 18–29
Betke U & Wickleder MS 2011, 'Sulfates of the refractory metals: Crystal structure and thermal behavior of Nb2O2(SO4)3, MoO2(SO4), WO(SO4)2, and two modifications of Re2O5(SO4)2', Inorganic chemistry, vol. 50, no. 3, pp 858–872, doi:10.1021/ic101455z
Beveridge TJ, Hughes MN, Lee H, Leung KT, Poole RK, Savvaidis I, Silver S & Trevors JT 1997, 'Metal–microbe interactions: Contemporary approaches', in RK Poole (ed.), Advances in microbial physiology, vol. 38, Academic Press, San Diego, pp. 177–243, ISBN 0-12-027738-7
Bogoroditskii NP & Pasynkov VV 1967, Radio and electronic materials, Iliffe Books, London
Booth VH & Bloom ML 1972, Physical science: a study of matter and energy, Macmillan, New York
Born M & Wolf E 1999, Principles of optics: Electromagnetic theory of propagation, interference and diffraction of light, 7th ed., Cambridge University Press, Cambridge, ISBN 0-521-64222-1
Brassington MP, Lambson WA, Miller AJ, Saunders GA & Yogurtçu YK 1980, 'The second- and third-order elastic constants of amorphous arsenic', Philosophical Magazine Part B, vol. 42, no. 1., pp. 127–148, doi:10.1080/01418638008225644
Brasted RC 1974, 'Oxygen group elements and their compounds', in The new Encyclopædia Britannica, vol. 13, Encyclopædia Britannica, Chicago, pp. 809–824
Brescia F, Arents J, Meislich H & Turk A 1975, Fundamentals of chemistry, 3rd ed., Academic Press, New York, p. 453, ISBN 978-0-12-132372-1
Brinkley SR 1945, Introductory general chemistry, 3rd ed., Macmillan, New York
Brown TL, LeMay HE, Bursten BE, Murphy CJ & Woodward P 2009, Chemistry: The Central Science, 11th ed., Pearson Education, New Jersey, ISBN 978-0-13-235-848-4
Burakowski T & Wierzchoń T 1999, Surface engineering of metals: Principles, equipment, technologies, CRC Press, Boca Raton, Fla, ISBN 0-8493-8225-4
Bychkov VL 2012, 'Unsolved Mystery of Ball Lightning', in Atomic Processes in Basic and Applied Physics, V Shevelko & H Tawara (eds), Springer Science & Business Media, Heidelberg, pp. 3–24, ISBN 978-3-642-25568-7
Carapella SC 1968a, 'Arsenic' in CA Hampel (ed.), The encyclopedia of the chemical elements, Reinhold, New York, pp. 29–32
Cerkovnik J & Plesničar B 2013, 'Recent Advances in the Chemistry of Hydrogen Trioxide (HOOOH), Chemical Reviews, vol. 113, no. 10), pp. 7930–7951, doi:10.1021/cr300512s
Chang R 1994, Chemistry, 5th (international) ed., McGraw-Hill, New York
Chang R 2002, Chemistry, 7th ed., McGraw Hill, Boston
Chedd G 1969, Half-way elements: The technology of metalloids, Doubleday, New York
Chen Z, Lee T-Y & Bosman G 1994, 'Electrical Band Gap of Porous Silicon', Applied Physics Letters, vol. 64, p. 3446, doi:10.1063/1.111237
Chizhikov DM & Shchastlivyi VP 1968, Selenium and selenides, translated from the Russian by EM Elkin, Collet's, London
Clementi E & Raimondi DL 1963, Atomic Screening Constants from SCF Functions, Journal of Chemical Physics, vol. 38, pp. 2868–2689, doi:10.1063/1.1733573
Clementi E, Raimondi DL & Reinhardt WP 1967, 'Atomic Screening Constants from SCF Functions. II. Atoms with 37 to 86 Electrons', Journal of Chemical Physics, vol. 47, pp. 1300–1306, doi:10.1063/1.1712084
Cordes EH & Scaheffer R 1973, Chemistry, Harper & Row, New York
Cotton SA 1994, 'Scandium, yttrium & the lanthanides: Inorganic & coordination chemistry', in RB King (ed.), Encyclopedia of inorganic chemistry, 2nd ed., vol. 7, John Wiley & Sons, New York, pp. 3595–3616, ISBN 978-0-470-86078-6
Cox PA 2004, Inorganic chemistry, 2nd ed., Instant notes series, Bios Scientific, London, ISBN 1-85996-289-0
Cross RJ, Saunders M & Prinzbach H 1999, 'Putting Helium Inside Dodecahedrane', Organic Letters, vol. 1, no. 9, pp. 1479–1481, doi:10.1021/ol991037v
Cverna F 2002, ASM ready reference: Thermal properties of metals, ASM International, Materials Park, Ohio, ISBN 0-87170-768-3
Donohoe J 1982, The Structures of the Elements, Robert E. Krieger, Malabar, Florida, ISBN 0-89874-230-7
Douglade J & Mercier R 1982, 'Structure cristalline et covalence des liaisons dans le sulfate d'arsenic(III), As2(SO4)3', Acta Crystallographica Section B, vol. 38, no. 3, pp. 720–723, doi:10.1107/S056774088200394X
Dunstan S 1968, Principles of chemistry, D. Van Nostrand Company, London
Du Plessis M 2007, 'A Gravimetric Technique to Determine the Crystallite Size Distribution in High Porosity Nanoporous Silicon, in JA Martino, MA Pavanello & C Claeys (eds), Microelectronics Technology and Devices–SBMICRO 2007, vol. 9, no. 1, The Electrochemical Society, New Jersey, pp. 133–142, ISBN 978-1-56677-565-6
Eby GS, Waugh CL, Welch HE & Buckingham BH 1943, The physical sciences, Ginn and Company, Boston
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, pp. 691–696, doi:10.1021/ed060p691
Edwards PP 1999, 'Chemically engineering the metallic, insulating and superconducting state of matter' in KR Seddon & M Zaworotko (eds), Crystal engineering: The design and application of functional solids, Kluwer Academic, Dordrecht, pp. 409–431
Edwards PP 2000, 'What, why and when is a metal?', in N Hall (ed.), The new chemistry, Cambridge University, Cambridge, pp. 85–114
Edwards PP, Lodge MTJ, Hensel F & Redmer R 2010, '...a metal conducts and a non-metal doesn't', Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, vol. 368, pp. 941–965, doi:10.1098rsta.2009.0282
Eichler R, Aksenov NV, Belozerov AV, Bozhikov GA, Chepigin VI, Dmitriev SN, Dressler R, Gäggeler HW, Gorshkov VA, Haenssler F, Itkis MG, Laube A, Lebedev VY, Malyshev ON, Oganessian YT, Petrushkin OV, Piguet D, Rasmussen P, Shishkin SV, Shutov, AV, Svirikhin AI, Tereshatov EE, Vostokin GK, Wegrzecki M & Yeremin AV 2007, 'Chemical characterization of element 112,' Nature, vol. 447, pp. 72–75, doi:10.1038/nature05761
Fraden JH 1951, 'Amorphous antimony. A lecture demonstration in allotropy', Journal of Chemical Education, vol. 28, no. 1, pp. 34–35, doi: 10.1021/ed028p34
Furuseth S, Selte K, Hope H, Kjekshus A & Klewe B 1974, 'Iodine oxides. Part V. The crystal structure of (IO)2SO4', Acta Chemica Scandinavica A, vol. 28, pp. 71–76, doi:10.3891/acta.chem.scand.28a-0071
Georgievskii VI 1982, 'Biochemical regions. Mineral composition of feeds', in VI Georgievskii, BN Annenkov & VT Samokhin (eds), Mineral nutrition of animals: Studies in the agricultural and food sciences, Butterworths, London, pp. 57–68, ISBN 0-408-10770-7
Gillespie RJ & Robinson EA 1959, 'The sulphuric acid solvent system', in HJ Emeléus & AG Sharpe (eds), Advances in inorganic chemistry and radiochemistry, vol. 1, Academic Press, New York, pp. 386–424
Glazov VM, Chizhevskaya SN & Glagoleva NN 1969, Liquid semiconductors, Plenum, New York
Glinka N 1965, General chemistry, trans. D Sobolev, Gordon & Breach, New York
Gösele U & Lehmann V 1994, 'Porous Silicon Quantum Sponge Structures: Formation Mechanism, Preparation Methods and Some Properties', in Feng ZC & Tsu R (eds), Porous Silicon, World Scientific, Singapore, pp. 17–40, ISBN 981-02-1634-3
Greaves GN, Greer AL, Lakes RS & Rouxel T 2011, 'Poisson's ratio and modern materials', Nature Materials, vol. 10, pp. 823‒837, doi:10.1038/NMAT3134
Greenwood NN & Earnshaw A 2002, Chemistry of the elements, 2nd ed., Butterworth-Heinemann, ISBN 0-7506-3365-4
Gschneidner KA 1964, 'Physical properties and interrelationships of metallic and semimetallic elements,' Solid State Physics, vol. 16, pp. 275‒426, doi:10.1016/S0081-1947(08)60518-4
Jauncey GEM 1948, Modern physics: A second course in college physics, D. Von Nostrand, New York
Jenkins GM & Kawamura K 1976, Polymeric carbons—carbon fibre, glass and char, Cambridge University Press, Cambridge
Keenan CW, Kleinfelter DC & Wood JH 1980, General college chemistry, 6th ed., Harper & Row, San Francisco, ISBN 0-06-043615-8
Keogh DW 2005, 'Actinides: Inorganic & coordination chemistry', in RB King (ed.), Encyclopedia of inorganic chemistry, 2nd ed., vol. 1, John Wiley & Sons, New York, pp. 2–32, ISBN 978-0-470-86078-6
Klein CA & Cardinale GF 1992, 'Young's modulus and Poisson's ratio of CVD diamond', in A Feldman & S Holly, SPIE Proceedings, vol. 1759, Diamond Optics V, pp. 178‒192, doi:10.1117/12.130771
Kneen WR, Rogers MJW & Simpson P 1972, Chemistry: Facts, patterns, and principles, Addison-Wesley, London
Kovalev D, Timoshenko VY, Künzner N, Gross E & Koch F 2001, 'Strong Explosive Interaction of Hydrogenated Porous Silicon with Oxygen at Cryogenic Temperatures', Physical Review Letters, vol. 87, pp. 068301–1–06831-4, doi:10.1103/PhysRevLett.87.068301
Kozyrev PT 1959, 'Deoxidized selenium and the dependence of its electrical conductivity on pressure. II', Physics of the solid state, translation of the journal Solid State Physics (Fizika tverdogo tela) of the Academy of Sciences of the USSR, vol. 1, pp. 102–110
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
Lagrenaudie J 1953, 'Semiconductive properties of boron' (in French), Journal de chimie physique, vol. 50, nos. 11–12, Nov-Dec, pp. 629–633
Lazaruk SK, Dolbik AV, Labunov VA & Borisenko VE 2007, 'Combustion and Explosion of Nanostructured Silicon in Microsystem Devices', Semiconductors, vol. 41, no. 9, pp. 1113–1116, doi:10.1134/S1063782607090175
Legit D, Friák M & Šob M 2010, 'Phase Stability, Elasticity, and Theoretical Strength of Polonium from First Principles,' Physical Review B, vol. 81, pp. 214118–1–19, doi:10.1103/PhysRevB.81.214118
Leith MM 1966, Velocity of sound in solid iodine, MSc thesis, University of British Coloumbia. Leith comments that, '... as iodine is anisotropic in many of its physical properties most attention was paid to two amorphous samples which were thought to give representative average values of the properties of iodine' (p. iii).
Lide DR & Frederikse HPR (eds) 1998, CRC Handbook of chemistry and physics, 79th ed., CRC Press, Boca Raton, Florida, ISBN 0-849-30479-2
Lidin RA 1996, Inorganic substances handbook, Begell House, New York, ISBN 1-56700-065-7
Lindegaard AL and Dahle B 1966, 'Fracture phenomena in amorphous selenium', Journal of Applied Physics, vol. 37, no. 1, pp. 262‒66, doi:10.1063/1.1707823
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. 2780–2783, doi:10.1021ja992866e
Marlowe MO 1970, Elastic properties of three grades of fine grained graphite to 2000°C, NASA CR‒66933, National Aeronautics and Space Administration, Scientific and Technical Information Facility, College Park, Maryland
Martienssen W & Warlimont H (eds) 2005, Springer Handbook of Condensed Matter and Materials Data, Springer, Heidelberg, ISBN 3-540-30437-1
Matula RA 1979, 'Electrical resistivity of copper, gold, palladium, and silver,' Journal of Physical and Chemical Reference Data, vol. 8, no. 4, pp. 1147–1298, doi:10.1063/1.555614
McQuarrie DA & Rock PA 1987, General chemistry, 3rd ed., WH Freeman, New York
Mendeléeff DI 1897, The Principles of Chemistry, vol. 2, 5th ed., trans. G Kamensky, AJ Greenaway (ed.), Longmans, Green & Co., London
Mercier R & Douglade J 1982, 'Structure cristalline d'un oxysulfate d'arsenic(III) As2O(SO4)2 (ou As2O3.2SO3)', Acta Crystallographica Section B, vol. 38, no. 3, pp. 1731–1735, doi:10.1107/S0567740882007055
Metcalfe HC, Williams JE & Castka JF 1966, Modern chemistry, 3rd ed., Holt, Rinehart and Winston, New York
Perkins D 1998, Mineralogy, Prentice Hall Books, Upper Saddle River, New Jersey, ISBN 0-02-394501-X
Pottenger FM & Bowes EE 1976, Fundamentals of chemistry, Scott, Foresman and Co., Glenview, Illinois
Qin J, Nishiyama N, Ohfuji H, Shinmei T, Lei L, Heb D & Irifune T 2012, 'Polycrystalline γ-boron: As hard as polycrystalline cubic boron nitride', Scripta Materialia, vol. 67, pp. 257‒260, doi:10.1016/j.scriptamat.2012.04.032
Rao CNR & Ganguly P 1986, 'A new criterion for the metallicity of elements', Solid State Communications, vol. 57, no. 1, pp. 5–6, doi:10.1016/0038-1098(86)90659-9
Raub CJ & Griffith WP 1980, 'Osmium and sulphur', in Gmelin handbook of inorganic chemistry, 8th ed., 'Os, Osmium: Supplement,' K Swars (ed.), system no. 66, Springer-Verlag, Berlin, pp. 166–170, ISBN 3-540-93420-0
Ravindran P, Fast L, Korzhavyi PA, Johansson B, Wills J & Eriksson O 1998, 'Density functional theory for calculation of elastic properties of orthorhombic crystals: Application to TiSi2', Journal of Applied Physics, vol. 84, no. 9, pp. 4891‒4904, doi:10.1063/1.368733
Reynolds WN 1969, Physical properties of graphite, Elsevier, Amsterdam
Rochow EG 1966, The metalloids, DC Heath and Company, Boston
Rock PA & Gerhold GA 1974, Chemistry: Principles and applications, WB Saunders, Philadelphia
Russell JB 1981, General chemistry, McGraw-Hill, Auckland
Slough W 1972, 'Discussion of session 2b: Crystal structure and bond mechanism of metallic compounds', in O Kubaschewski (ed.), Metallurgical chemistry, proceedings of a symposium held at Brunel University and the National Physical Laboratory on the 14, 15 and 16 July 1971, Her Majesty's Stationery Office [for the] National Physical Laboratory, London
Slyh JA 1955, 'Graphite', in JF Hogerton & RC Grass (eds), Reactor handbook: Materials, US Atomic Energy Commission, McGraw Hill, New York, pp. 133‒154
Smith A 1921, General chemistry for colleges, 2nd ed., Century, New York
Sneed MC 1954, General college chemistry, Van Nostrand, New York
Wickleder MS, Pley M & Büchner O 2006, 'Sulfates of precious metals: Fascinating chemistry of potential materials', Zeitschrift für anorganische und allgemeine chemie, vol. 632, nos. 12–13, p. 2080, doi:10.1002/zaac.200670009
Wickleder MS 2007, 'Chalcogen-oxygen chemistry', in FA Devillanova (ed.), Handbook of chalcogen chemistry: new perspectives in sulfur, selenium and tellurium, RSC, Cambridge, pp. 344–377, ISBN 978-0-85404-366-8
Wilson JR 1965, 'The structure of liquid metals and alloys', Metallurgical reviews, vol. 10, p. 502
Wilson AH 1966, Thermodynamics and statistical mechanics, Cambridge University, Cambridge
Witczak Z, Goncharova VA & Witczak PP 2000, 'Irreversible effect of hydrostatic pressure on the elastic properties of polycrystalline tellurium', in MH Manghnani, WJ Nellis & MF Nicol (eds), Science and technology of high pressure: Proceedings of the International Conference on High Pressure Science and Technology (AIRAPT-17), Honolulu, Hawaii, 25‒30 July 1999, vol. 2, Universities Press, Hyderabad, pp. 822‒825, ISBN 81-7371-339-1
Witt SF 1991, 'Dimethylmercury', Occupational Safety & Health Administration Hazard Information Bulletin, US Department of Labor, February 15, accessed 8 May 2015
Wittenberg LJ 1972, 'Volume contraction during melting; emphasis on lanthanide and actinide metals', The Journal of Chemical Physics, vol. 56, no. 9, p. 4526, doi:10.1063/1.1677899
Young RV & Sessine S (eds) 2000, World of chemistry, Gale Group, Farmington Hills, Michigan
Zhigal'skii GP & Jones BK 2003, Physical properties of thin metal films, Taylor & Francis, London, ISBN 0-415-28390-6
Zuckerman & Hagen (eds) 1991, Inorganic reactions and methods, vol, 5: The formation of bonds to group VIB (O, S, Se, Te, Po) elements (part 1), VCH Publishers, Deerfield Beach, Fla, ISBN 0-89573-250-5
A metal (from Greek μέταλλον métallon, "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typically malleable (they can be hammered into thin sheets) or ductile (can be drawn into wires). A metal may be a chemical element such as iron, or an alloy such as stainless steel.
In physics, a metal is generally regarded as any substance capable of conducting electricity at a temperature of absolute zero. Many elements and compounds that are not normally classified as metals become metallic under high pressures. For example, the nonmetal iodine gradually becomes a metal at a pressure of between 40 and 170 thousand times atmospheric pressure. Equally, some materials regarded as metals can become nonmetals. Sodium, for example, becomes a nonmetal at pressure of just under two million times atmospheric pressure.
In chemistry, two elements that would otherwise qualify (in physics) as brittle metals—arsenic and antimony—are commonly instead recognised as metalloids, on account of their predominately non-metallic chemistry. Around 95 of the 118 elements in the periodic table are metals (or are likely to be such). The number is inexact as the boundaries between metals, nonmetals, and metalloids fluctuate slightly due to a lack of universally accepted definitions of the categories involved.
In astrophysics the term "metal" is cast more widely to refer to all chemical elements in a star that are heavier than the lightest two, hydrogen and helium, and not just traditional metals. A star fuses lighter atoms, mostly hydrogen and helium, into heavier atoms over its lifetime. Used in that sense, the metallicity of an astronomical object is the proportion of its matter made up of the heavier chemical elements.Metals comprise 25% of the Earth's crust and are present in many aspects of modern life. The strength and resilience of some metals has led to their frequent use in, for example, high-rise building and bridge construction, as well as most vehicles, many home appliances, tools, pipes, and railroad tracks. Precious metals were historically used as coinage, but in the modern era, coinage metals have extended to at least 23 of the chemical elements.The history of metals is thought to begin with the use of copper about 11,000 years ago. Gold, silver, iron (as meteoric iron), lead, and brass were likewise in use before the first known appearance of bronze in the 5th millennium BCE. Subsequent developments include the production of early forms of steel; the discovery of sodium—the first light metal—in 1809; the rise of modern alloy steels; and, since the end of World War II, the development of more sophisticated alloys.
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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