Post-transition metal
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In chemistry, the term post-transition metal is used to describe the category of metallic elements to the right of the transition elements on the periodic table[1][2]. IUPAC defines "transition elements" as either the elements in groups 3–11 or the elements in groups 3–12[3]. According to the first definition, post-transition metals include group 12—zinc, cadmium, and mercury. This collection of elements is illustrated by the element boxes to the right. Occasionally germanium, antimony, and/or polonium are also included as metals, although these are usually considered to be metalloids. According to the second definition of transition elements, group 12 would not be included as a post-transition metal. An examination of textbooks and monographs in 2003 revealed that both definitions are used with roughly equal frequency[4].
In the 1950s, most inorganic chemistry textbooks defined transition elements as excluding group 11—copper, silver, and gold in addition to group 12[4]. A third definition of post-transition metal that includes group 11 and group 12 elements is no longer recommended by IUPAC[3] but is still used on occasion[5][6].
Poor metals
The trivial name poor metals is sometimes applied to the metallic elements in the p-block of the periodic table. Their melting and boiling points are generally lower than those of the transition metals and their electronegativity higher, and they are also softer. They are distinguished from the metalloids, however, by their significantly higher boiling points in the same row.
"Poor metals" is not a rigorous IUPAC-approved nomenclature, but the grouping is generally taken to include aluminium, gallium, indium, tin, thallium, lead, and bismuth. Occasionally germanium, antimony, and polonium are also included, although these are usually considered to be metalloids or "semi-metals". Elements 113, 114, 115, and 116, which are currently allocated the systematic names ununtrium, ununquadium, ununpentium, and ununhexium, would likely exhibit properties characteristic of poor metals;[citation needed] however sufficient quantities of them have not yet been synthesized to examine their chemical properties.
| 13 | 14 | 15 | 16 |
|---|---|---|---|
| Al Aluminium | |||
| Ga Gallium |
Ge Germanium | ||
| In Indium |
Sn Tin |
Sb Antimony | |
| Tl Thallium |
Pb Lead |
Bi Bismuth |
Po Polonium |
| Uut ununtrium |
Uuq ununquadium |
Uup ununpentium |
Uuh ununhexium |
References
- ^ General Chemistry: Principles and Structure (5th ed.), by James E. Brady, page 96. Published by Wiley, 1990. ISBN 0471621315, 9780471621317
- ^ Instant Notes in Inorganic Chemistry (2nd ed.), by P.A. Cox, page 185–186. Published by Garland Science/BIOS Scientific Publishers, 2004. ISBN 1859962890, 9781859962893
- ^ a b Nomenclature of Inorganic Chemistry, IUPAC Recommendations (2005) IR 3-6.2 p 51
- ^ a b William B. Jensen (2003). "The Place of Zinc, Cadmium, and Mercury in the Periodic Table". Journal of Chemical Education 80 (8): 952–961.
- ^ Introductory solid state physics (2nd ed.), by H.P. Myers, page 216. Published by Taylor & Francis, 1997. ISBN 074840659X, 9780748406593
- ^ Bioinorganic Chemistry, by K. Hussain Reddy, page 69. Published by New Age International, 2003. ISBN 8122414370, 9788122414370
