All the alkali metal halides are soluble in water except for lithium fluoride (LiF), which is insoluble in water due to its very high lattice enthalpy.
ˈɔːl ðɪ ˈælkəlˌaɪ mˈɛɾəl hˈælaɪdz ɑːɹ sˈɑːljuːbəl ɪn wˈɔːɾɚɹ ɛksˈɛpt fɔːɹ lˈɪθiəm flˈʊɹɹaɪd lˈaɪ ˈɛf, wˌɪtʃ ɪz ɪnsˈɑːljuːbəl ɪn wˈɔːɾɚ dˈuː tʊ ɪts vˈɛɹi hˈaɪ lˈæɾɪs ɛnθˈælpi.