Lists of metalloids the literature can also be found to the categorisation of other elements as metalloids. These elements include: hydrogen, nitrogen, sulfur, zinc, gallium, iodine, lead, and radon (citations are for references other than those listed above). Lists of metalloids This is a list of sources that each list metalloids: elements classified as metalloids. The sources are listed in chronological order. Lists of metalloids differ since there is no rigorous definition of metalloid (or its occasional alias, 'semi-metal'). Individual lists share common ground, with variations occurring at the margins. The elements most often regarded as metalloids are boron, silicon, germanium, arsenic, antimony
Metalloid of sulfur contaminants from natural gas. Titanium doped aluminium has been identified as a substitute for expensive noble metal catalysts used in the production of industrial chemicals. Compounds of boron, silicon, arsenic, and antimony have been used as flame retardants. Boron, in the form of borax, has been used as a textile flame retardant since at least the 18th century. Silicon compounds such as silicones, silanes, silsesquioxane, silica, and silicates, some of which were developed as alternatives to more toxic halogenated products, can considerably improve the flame retardancy of plastic materials. Arsenic compounds such as sodium arsenite or sodium arsenate