Based on the analysis of known valu

Based on the analysis of known values of decomposition point, it is evident that in the period of AM position thetemperature of hydrofluorides grows (Table 5). One would expect the similar change in properties for fluorides ofalkali metals saturated by HF. The references conclude that the boiling point Тb (idem Тdec) of trihydrofluorides andtetrahydrofluorides of alcali metals and alkaline-earth metals depends primarily on the order number of the metal inthe group (on nuclear charge of metal atom, to be precise), and secondly - on HF content. The first statement is incontradiction with Mendeleev’s periodic law, which states that the chemical properties of similar substances changemonotonously according to location in table6. The second statement suggests that trihydro- and tetrahydrofluoridesare in fact one substance, but it is disproved by the facts of their synthesis and identification7.