 In addition to compounds where xenon forms a chemical bond , xenon can form <unk> — substances where xenon atoms or pairs are trapped by the crystalline lattice of another compound . One example is xenon hydrate ( Xe <unk> 5 @.@ 75 H2O ) , where xenon atoms occupy vacancies in a lattice of water molecules . This <unk> has a melting point of 24 ° C. The <unk> version of this hydrate has also been produced . Another example is Xe hydride ( Xe ( H2 ) 8 ) , in which xenon pairs ( <unk> ) are trapped inside solid hydrogen . Such <unk> <unk> can occur naturally under conditions of high pressure , such as in Lake <unk> underneath the Antarctic ice sheet . <unk> formation can be used to <unk> <unk> xenon , argon and krypton . 
