Tottle (1966)

[Rene]

I was drawn to the attached periodic table by the strange-looking arrangement of dividing lines, one "full" and one dashed, in the p-block.

Semimetals

Ge, As, Se, Sn, Sb, Te, Bi and Po are shown as semi-metals. Tottle does not explain the basis for this division.

Showing Sn as a semi-metal or metalloid is dubious. Sure, white-Sn becomes gray-Sn at a temperature of below 13.2 °C but even here it has the electronic band structure of a semi-metal.

The same can be said for Po which has electronic band structure of a true metal, unlike the situation in As, Sb and Bi, all of which have electronic band structures of semi-metals.

Metals and nonmetals

Starting with H, note the left to right path of the full dividing line between metals and nonmetals is continuous, except for the unique break above Be, presumably to show that there is no element above Be. This is actually not well thought-out since the metallic or nonmetallic status of the IIA elements is not then clarified.

Tottle is further interesting since, as well as referring to metals and nonmetals in the periodic table sense he later includes a chapter on Metals and alloys, and a chapter on Non-metallic materials. Some examples given by him of non-metallic materials are alumina, magnesia, graphite, beryllia, titanium carbide, glass, rubber, nylon and wood. So, he here is mixing nonmetallic elements and nonmetallic materials (which is fine).

He gets into trouble in his chapter on Metals and alloys, since he includes some discussion on interstitial solid solutions, such as cementite Fe3C, which is an insulator, and intermetallic compounds, which appears fine on the surface, until one realises that some intermetallic compounds are semiconductors, such as FeGa3, RuGa3, and IrGa3. I have never heard of semiconducting or insulating metals or alloys.

• Tottle CR 1974, The Science of Engineering Materials,  reprint of 1966 ed., Heinemann Educational Books, London, p. 20

René