1212131415161718 H He LiBeBCNOFNeNaMgAlSiPSClArKCaZnGaGeAsSeBrKrRbSrCdInSnSbTeIXeCsBaHgTlPbBiPoAtRnFrRaCnNhFlMcLvTsOg Condensed periodic table showing a typical dividing line.
Metal-nonmetal dividing line (arbitrary): between , , , , , ,
The dividing line between metals and nonmetals can be found, in varying configurations, on some representations of the periodic table of the elements (see mini-example, right). 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 (Li, Be, Al, Ge, Sb, Po) lie just below the line.Horvath 1973, p. 336
The location and therefore usefulness of the line is debated. It cuts through the metalloids, elements that share properties between metals and nonmetals, in an arbitrary manner, since the transition between metallic and non-metallic properties among these elements is gradual.
Names This line has been called the amphoteric line,Levy 2001, p. 158 the metal-nonmetal line,Tarendash 2001, p. 78 the metalloid line,Thompson 1999DiSalvo 2000, p. 1800 the semimetal line,Whitley 2009 or the staircase. While it has also been called the Zintl borderKing 2005, p. 6006 or the Zintl lineHerchenroeder & Gschneidner 1988De Graef & McHenry 2007, p. 34 these terms instead refer to a vertical line sometimes drawn between groups 13 and 14. This particular line was named by Laves in 1941.Kniep 1996, p. xix It differentiates group 13 elements from those in and to the right of group 14. The former generally combine with electropositive metals to make intermetallic compounds whereas the latter usually form salt-like compounds.Nordell & Miller 1999, p. 579
History References to a dividing line between metals and nonmetals appear in the literature as far back as at least 1869.Hinrichs 1869, p. 115. In his article Hinrichs included a periodic table, organized by atomic weight, but this did not show a metal-nonmetal dividing line. Rather, he wrote that, "... elements of like properties or their compounds of like properties, form groups bounded by simple lines. Thus a line drawn through C, As, Te, separates the elements, having metallic lustre from those not having such lustre. The gaseous elements form a small group by themselves, the condensible [sic] chlorine forming the boundary ... So also the boundary lines for other properties may be drawn." In 1891, Walker published a periodic "tabulation" with a diagonal straight line drawn between the metals and the nonmetals.Walker 1891, p. 252 In 1906, Alexander Smith published a periodic table with a zigzag line separating the nonmetals from the rest of elements, in his highly influentialMiles & Gould 1976, p. 444: "His 'Introduction to General Inorganic Chemistry,' 1906, was one of the most important textbooks in the field during the first quarter of the twentieth century." textbook Introduction to General Inorganic Chemistry.Smith 1906, pp. 408, 410 In 1923, Horace G. Deming, an American chemist, published short (Mendeleev style) and medium (18-column) form periodic tables.Deming 1923, pp. 160, 165 Each one had a regular stepped line separating metals from nonmetals. Merck and Company prepared a handout form of Deming's 18-column table, in 1928, which was widely circulated in American schools. By the 1930s Deming's table was appearing in handbooks and encyclopaedias of chemistry. It was also distributed for many years by the Sargent-Welch Scientific Company.Abraham, Coshow & Fix, W 1994, p. 3Emsley 1985, p. 36Fluck 1988, p. 432
Double line variant A dividing line between metals and nonmetals is sometimes replaced by two dividing lines. One line separates metals and metalloids; the other metalloids and nonmetals.Brown & Holme 2006, p. 57Swenson 2005
Concerns Mendeleev wrote that, "It is, however, impossible to draw a strict line of demarcation between metals and nonmetals, there being many intermediate substances".Mendeléeff 1897, p. 23 Several other sources note confusion or ambiguity as to the location of the dividing line;MacKay & MacKay 1989, p. 24Norman 1997, p. 31 suggest its apparent arbitrarinessWhitten, Davis & Peck 2003, p. 1140 provides grounds for refuting its validity;Roher 2001, pp. 4–6 and comment as to its misleading, contentious or approximate nature.Hawkes 2001, p. 1686Kotz, Treichel & Weaver 2005, pp. 79–80Housecroft & Constable 2006, p. 322 Deming himself noted that the line could not be drawn very accurately.Deming 1923, p. 381
Notes
Citations
References Abraham M, Coshow, D & Fix, W 1994, Periodicity: A source book module, version 1.0. Chemsource, Inc., New York, viewed 26 Aug 11 Brown L & Holme T 2006, Chemistry for engineering students, Thomson Brooks/Cole, Belmont CA, De Graef M & McHenry ME 2007, Structure of materials: an introduction to crystallography, diffraction and symmetry, Cambridge University Press, Cambridge, Deming HG 1923, General chemistry: An elementary survey, John Wiley & Sons, New York Emsley J, 1985 'Mendeleyev's dream table', New Scientist, 7 March, pp. 32–36 Glinka N 1959, General chemistry, Foreign Languages Publishing House, Moscow Hinrichs GD 1869, 'On the classification and the atomic weights of the so-called chemical elements, with particular reference to Stas's determinations', Proceedings of the American Association for the Advancement of Science, vol. 18, pp. 112–124 Housecroft CE & Constable EC 2006, Chemistry, 3rd ed., Pearson Education, Harlow, England, King RB (ed.) 2005, Encyclopedia of inorganic chemistry, 2nd ed., John Wiley & Sons, Chichester, p. 6006, Kniep R 1996, 'Eduard Zintl: His life and scholarly work', in SM Kauzlarich (ed.), Chemistry, structure and bonding of Zintl phases and ions, VCH, New York, pp. xvii–xxx, Kotz JC, Treichel P & Weaver GC 2005, Chemistry & chemical reactivity, 6th ed., Brooks/Cole, Belmont, CA, Levy J 2011, The bedside book of chemistry, Pier 9, Millers Point, Sydney, MacKay KM & MacKay RA 1989, Introduction to modern inorganic chemistry, 4th ed., Blackie, Glasgow, Mendeléeff DI 1897, The principles of chemistry, vol. 1, 5th ed., trans. G Kamensky, AJ Greenaway (ed.), Longmans, Green & Co., London Miles WD & Gould RF 1976, American chemists and chemical engineers, vol. 1, American Chemical Society, Washington Norman NC 1997, Periodicity and the s- and p-block elements, Oxford University, Oxford, Roher GS 2001, Structure and bonding in crystalline materials, Cambridge University Press, Cambridge, Smith A 1906, Introduction to general inorganic chemistry, The Century Company, New York Swenson J 2005, 'Classification of noble gases', in Ask a scientist, Chemistry archive Tarendash AS 2001, Let's review: Chemistry, the physical setting, Barron's Educational Series, Hauppauge, New York, Walker J 1891, 'On the periodic tabulation of the elements', The Chemical News, vol. LXIII, no. 1644, May 29, pp. 251–253 Whitley K 2009, Periodic table: Metals, non-metals, and semi-metals Whitten KW, Davis RE & Peck LM 2003, A qualitative analysis supplement, 7th ed., Thomson Brooks/Cole, Belmont, CA,
External links Summary of an ACS presentation on the "myth" of the dividing line