Post-transition metal


Post-transition metal
Post-transition metals
Group # 12 13 14 15 16
Period
4 30
Zn
31
Ga
32
Ge
5 48
Cd
49
In
50
Sn
51
Sb
6 80
Hg
81
Tl
82
Pb
83
Bi
84
Po
Atomic numbers show state at STP
Solids Liquids
Transition metals
Post-transition metals
Metalloids

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] Which elements should be included in the post-transition metals is still widely disputed.

Contents

Included elements

A first IUPAC definition states "[T]he elements of groups 3–12 are the d-block elements. These elements are also commonly referred to as the transition elements, though the elements of group 12 are not always included".[3] Depending on the inclusion of group 12 as a transition metal, the post-transition metals may or may not include the group 12 elementszinc, cadmium, and mercury. An examination of textbooks and monographs in 2003 revealed that the group 12 elements are included and excluded with roughly equal frequency.[4]

A second IUPAC definition states "An element whose atom has an incomplete d sub-shell, or which can give rise to cations with an incomplete d sub-shell."[5] Based on this definition one could argue group 12 should be split with mercury and copernicium as transition metals, and zinc and cadmium as post-transition metals. Of relevance is the synthesis of mercury(IV) fluoride, which establishes mercury as a transition metal.[6][7] Copernicium is predicted to have an electron configuration similar to mercury, predicting it as a transition metal as well.

Occasionally germanium, antimony, and/or polonium are also included, although these are usually considered to be metalloids.[8]

In the 1950s, most inorganic chemistry textbooks defined transition elements as excluding group 11copper, silver, and gold in addition to group 12.[4]

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 that of the transition metals and their electronegativity higher, and they are also softer. They are distinguished from the metalloids by their significantly higher boiling points and conductivity 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; 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

  1. ^ Brady, James E. (1990). General Chemistry: Principles and Structure (5th ed.). Wiley. p. 96. ISBN 9780471621317. http://books.google.com/?id=UVlGAAAAYAAJ&dq=post-transition+metal+brady&q=post-transition+%22just+to+the+right%22#search_anchor. 
  2. ^ Cox, P. A. (2004). Instant Notes in Inorganic Chemistry (2nd ed.). Garland Science/BIOS Scientific Publishers. pp. 185–186. ISBN 9781859962893. http://books.google.com/books?id=8yQOhvD3tWcC&pg=PA185#v=onepage&q=&f=false. 
  3. ^ International Union of Pure and Applied Chemistry (2005). Nomenclature of Inorganic Chemistry (IUPAC Recommendations 2005). Cambridge (UK): RSCIUPAC. ISBN 0-85404-438-8. pp. IR-3.5. Electronic version.
  4. ^ a b Jensen, William B. (2003). "The Place of Zinc, Cadmium, and Mercury in the Periodic Table". Journal of Chemical Education 80 (8): 952–961. Bibcode 2003JChEd..80..952J. doi:10.1021/ed080p952. 
  5. ^ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version:  (2006–) "Transition Metal".
  6. ^ Wang, Xuefang; Andrews, Lester; Riedel, Sebastian; Kaupp, Martin (2007). "Mercury Is a Transition Metal: The First Experimental Evidence for HgF4". Angew. Chem. Int. Ed. 46 (44): 8371–8375. doi:10.1002/anie.200703710. PMID 17899620. 
  7. ^ "Elusive Hg(IV) species has been synthesized under cryogenic conditions". EVISA news. October 12, 2007. http://www.speciation.net/Public/News/2007/10/12/3303.html. Retrieved December 2, 2007. 
  8. ^ Egdell, R. G. (2007). "Post Transition Metal Chemistry Lecture 1" (PDF). WebLearn - Oxford Campus, Department of Chemistry. http://weblearn.ox.ac.uk/site/mathsphys/chem/year3/mt2007/posttrans/resources/lecture%201.pdf. Retrieved December 2, 2007. 

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