|Post-transition metals in the periodic table|
|Atomic number color shows state at STP:
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. Which elements should be included in the post-transition metals is still widely disputed.
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". Depending on the inclusion of group 12 as a transition metal, the post-transition metals may or may not include the group 12 elements—zinc, 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.
A second IUPAC definition for transition metals states "An element whose atom has an incomplete d sub-shell, or which can give rise to cations with an incomplete d sub-shell." 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. Copernicium is predicted to have an electron configuration similar to mercury, predicting it as a transition metal as well.
Poor metals 
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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 period.
"Poor metals" is not a rigorous IUPAC-approved nomenclature, but the grouping is generally taken to include aluminium, gallium, indium, tin, thallium, lead, bismuth and polonium. Occasionally germanium and antimony 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 names ununtrium, flerovium, ununpentium, and livermorium, would likely exhibit properties characteristic of poor metals; sufficient quantities of them have not yet been synthesized to examine their chemical properties.
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- "Elusive Hg(IV) species has been synthesized under cryogenic conditions". EVISA news. October 12, 2007. Retrieved December 2, 2007.
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