linguistic:translation, quality:correction, linguistic:voice_change, structural:reformatting, structural:summarization
Halides and pseudohalides

The halides ScX, where X= Cl, Br, or I, are very soluble in water, but ScF is insoluble. In all four halides, the scandium is 6-coordinated. The halides are Lewis acids; for example, ScF dissolves in a solution containing excess fluoride ion to form. The coordination number 6 is typical for Sc(III). In the larger Y and La ions, coordination numbers of 8 and 9 are common. Scandium triflate is sometimes used as a Lewis acid catalyst in organic chemistry.