the periodic table that are softer and have lower melting points than the metals traditionally used for tools.' Post-transition metals An early usage of this name is recorded by Deming, in 1940, in his well-known book Fundamental Chemistry. He treated the transition metals as finishing at group 10 (nickel, palladium and platinum). He referred to the ensuing elements in periods 4 to 6 of the periodic table (copper to germanium; silver to antimony; gold to polonium)—in view of their underlying d10 electronic configurations—as post-transition metals. Semimetals In modern use, the term 'semimetal' sometimes refers, loosely or explicitly, to metals with incomplete metallic character in crystalline structure, electrical conductivity or electronic structure. Examples include gallium, ytterbium, bismuth, mercury and neptunium. Metalloids, which are in-between elements that are neither metals nor nonmetals, are also sometimes instead called semimetals. The elements commonly recognised as metalloids are boron, silicon, germanium, arsenic, antimony and tellurium. In old chemistry, before the publication in 1789 of Lavoisier's 'revolutionary' Elementary Treatise on Chemistry, a semimetal was a metallic element with 'very imperfect ductility and malleability' such as zinc, mercury or bismuth. Soft metals Scott and Kanda refer to the metals in groups 11 to 15, plus platinum in group 10, as soft metals, excluding the very active metals, in groups 1−3. They note many important non-ferrous alloys are made from metals in this class, including sterling silver, brass (copper and zinc), and bronzes (copper with tin, manganese and nickel). Transition metals Historically, the transition metal series "includes those elements of the Periodic Table which 'bridge the gap' between the very electropositive alkali and allkaline earth metals and the electronegative non-metals of the groups: nitrogen-phosphorus, oxygen-sulfur, and the halogens." Cheronis, Parsons and Ronneberg wrote that, "The transition metals of low melting point form a block in the Periodic Table: those of Groups II 'b' [zinc, cadmium, mercury], III 'b' [aluminium, gallium, indium, thallium], and germanium, tin and lead in Group IV. These metals all have melting points below 425 °C." Notes Sources Citations Indexed references Abd-El-Aziz AS, Carraher CE, Pittman CU, Sheats JE & Zeldin M 2003, Macromolecules Containing Metal and Metal-Like Elements, vol. 1, A Half-Century of Metal- and Metalloid-Containing Polymers, John Wiley & Sons, Hoboken, New Jersey, Abrikosov AA 1988, Fundamentals of the theory of metals, North Holland, Amsterdam, Aleandri LE & Bogdanović B 2008, 'The magnesium route to active metals and intermetallics, in A Fürstner (ed.),