Fluorine occurrence

Some elements contain a fixed number of neutrons, as with fluorine (P = 9, N = 10) and phosphorus (P = 15, N = 16). For their natural occurrences, atoms of any one such element all have the same mass (F= 19 P = 31). 

Kuznetsov, Polyakov and Stangrit [317, 318] and on KC1 - NaCl - NaF -K2NbF7 by Kovalev, Ioffe and Datlina [319], all in the concentration range of up to 20-25% mass of K2NbF7. In all cases, maximum electro-conductivity was observed at concentrations of about 5-10% mass of K2NbF7. The peaking of the electro-conductivity is explained by the occurrence of two processes with opposite characters. The increase in electro-conductivity is related to the increase in the concentration of potassium ions [319] and fluorine ions [317, 318], whereas the drop in conductivity results from a decrease in free volume due to an increase in NbF72 ion concentration. 

The oxidation number of oxygen is —2 in most of its compounds. Exceptions are its compounds with fluorine (in which case, the previous statement takes precedence) and its occurrence as peroxides (022-), superoxides (02 ), and ozonides (03 ). 

Another point of contention has been the extent to which, if any, SbFj is reduced to SbFs upon intercalation. Although chemical analyses have shown an F Sb ratio of 5 1 (Lll, M5), Sb Mossbauer measurements (B24) indicated partial reduction of Sb(V) to Sb(III). On the other hand, mass-spectral measurements as a function of temperature (S15) showed only SbFs, evolved in stages, with no fluorocarbons emitted at any time. The latter are usually an indication of partial reduction of the intercalant and fluorination of the graphite host. Wide-line, F-NMR chemical-shifts are consistent with either SbFj or SbFe, but not with SbFs, but the occurrence of fluorine exchange could produce minor amounts of trivalent species (FI 1) this point is thus still controversial, and will be alluded to again. 

Harper DB, D O Hagan, CD Murphy (2003) Fluorinated natural products occurrence and biosynthesis. Handbook Environ Chem 3P 141-169. 

During preparation of fluorotrinitromethane, an instrumental method can be used to avoid occurrence of dangerous over-fluorination of nitroform. 

The deficit of I, Co, Mn, and Zn, moderate excess of Si and disturbed ratios of trace metals to I and Si are characteristic features of the biogeochemical food web of this Pre-Volga sub-region of biosphere. Most of its natural water sources have a decreased content of fluorine. These peculiarities of biogeochemical food web favor the occurrence of tooth decay (caries) and endemic goiter. 

P. Pitter, Forms of occurrence of fluorine in drinking water. Water Res. 19 (1985) 281-284. 

The addition of lithium fluoride, due to its solubility in a fluorine bath, can suppress the occurrence of the anode effect.2 Nakajima and co-workers reported that the carbon/hydrogen fluoride/fluorine system formed the graphite fluoride intercalation compound C4F as a solid... 

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