Salt-like (saline) Carbides
Salt-like carbides are composed of highly electropositive elements such as the alkali metals, alkaline earths, and group 3 metals including scandium, yttrium and lanthanum. Aluminium from group 13 forms carbides, but gallium, indium and thallium do not. These materials feature isolated carbon centers, often described as "C4−", in the methanides or methides; two-atom units, "C22−", in the acetylides; and three-atom units, "C34−", in the sesquicarbides. The graphite intercalation compound KC8, prepared from vapour of potassium and graphite, and the alkali metal derivatives of C60 are not usually classified as carbides.
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