In the 1950s, most inorganic chemistry textbooks defined transition elements as excluding group 11—copper, silver, and gold in addition to group 12. A third definition of post-transition metal that includes group 11 and group 12 elements is no longer recommended by IUPAC but is still used on occasion.

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.