XPS analysis of this element must be careful not to confuse it with a similar binding energy peak from zinc. Sodium, oxygen, and this element make up Graham’s salt. The Gutmann–Beckett method uses NMR spectroscopy of this element’s 31 isotope. A triphenyl (-5[1])derivative of this element (10[1])is found in Vaska’s complex (10[1])and can also be used (10[1])to create ylides (“ILL-ids”) in the (10[1])Wittig (10[1])reaction. Oxygen and (10[1])this element can form anions designated as ortho or pyro, and also forms a triprotic acid. (-5[1])Alongside nitrogen and potassium, fertilizers report the content (10[1])of this (10[1])element. For 10 points, name this element with red (-5[1])and white varieties used to light (10[1])matches. ■END■ (10[2])