Wikipedia:WikiProject Elements/Legends

Category

 * This section has been deprecated; due to the bewildering variety of slightly different categories in the literature and disagreement on their boundaries, a strict scheme based on blocks has been adopted as of January 2021.

Nonmetals are subdevided in diatomic nonmetals, polyatomic nonmetals (and noble gases, unchanged). The category other/poor metals is renamed into post-transition metals without further changes. This is the new scheme:
 * Note: as of 17 August 2013, the English wikipedia has changed categorisation and background colors of nonmetal elements. Below is the new categorisation scheme. Differences are about these old categories: "other nonmetal", "halogen", "post-transition metals"

Usage

 * See for example: compact extended periodic table
 * Example Periodic table (32 columns, micro), extended:

Categories, reduced set
When a reduced category set, or more general category set, is used, below are their color legends. It is unadvised to use different category levels (different legend rows) in a single table.