It combines directly with fluorine at Ordinary temperature, and with chlorine, bromine and sulphur on heating.
The following, however, are negative towards the remaining elements which are more or less positive:-Fluorine, chlorine, bromine, iodine, oxygen, sulphur, selenium, tellurium.
The elements are usually divided into two classes, the metallic and the non-metallic elements; the following are classed as non-metals, and the remainder as metals: Of these hydrogen, chlorine, fluorine, oxygen, nitrogen, argon, neon, krypton, xenon and helium are gases, bromine is a liquid, and the remainder are solids.
Balard completed for many years Berzelius's group of " halogen " elements; the remaining member, fluorine, notwithstanding many attempts, remained unisolated until 1886, when Henri Moissan obtained it by the electrolysis of potassium fluoride dissolved in hydrofluoric acid.
Rosenbuschite, hiortdahlite, and some other rare members containing zirconium and fluorine, occur as accessory constituents in the nephelinesyenite of southern Norway.
Fluorine is also often an essential constituent, and titanium is sometimes present.
It is attacked rapidly by fluorine at ordinary temperature, and by chlorine when heated in a current of the gas.
Silicon fluoride, SiF4, is formed when silicon is brought into contact with fluorine (Moissan); or by decomposing a mixture of acid potassium fluoride and silica, or of calcium fluoride and silica with concentrated sulphuric acid.
Tantalum pentafluoride, TaF5, for a long time only known in solution, may be obtained by passing fluorine over an alloy of tantalum and aluminium, and purifying by distillation in a vacuum.
Moissan by acting with fluorine on the carbide.
It combines with fluorine at loo° C., and when heated with chlorine it forms a mixture of chlorides.
FLUORINE (symbol F, atomic weight iv), a chemical element of the halogen group. It is never found in the uncombined condition, but in combination with calcium as fluor-spar CaF2 it is widely distributed; it is also found in cryolite Na3A1F6, in fluor-apatite, CaF 2.3Ca 3 P 2 O 8, and in minute traces in seawater, in some mineral springs, and as a constituent of the enamel of the teeth.
The fluorine, which is liberated as a gas at the anode, is passed through a well cooled platinum vessel, in order to free it from any acid fumes that may be carried over, and finally through two platinum tubes containing sodium fluoride to remove the last traces of hydrofluoric acid; it is then collected in a platinum tube closed with fluor-spar plates.
Soc., 18 94, 6 5, p. 393) obtained fluorine by heating potassium fluorplumbate 3KF HF PbF 4.
At 200° C. this salt decomposes, giving off hydrofluoric acid, and between 230-250° C. fluorine is liberated.
Fluorine is a pale greenish-yellow gas with a very sharp smell; its specific gravity is 1.265.
Only one compound of hydrogen and fluorine is known, namely hydrofluoric acid, HF or H 2 F 2, which was first obtained by C. Scheele in 1771 by decomposing fluor-spar with concentrated sulphuric acid, a method still used for the commercial preparation of the aqueous solution of the acid, the mixture being distilled from leaden retorts and the acid stored in leaden or gutta-percha bottles.
The atomic weight of fluorine has been determined by the conversion of calcium, sodium and potassium fluorides into the corresponding sulphates.
Berthelot); it also unites directly with fluorine, producing, chiefly, carbon tetrafluoride CF 4.
When magnesium is heated in fluorine or chlorine or in the vapour of bromine or iodine there is a violent reaction, and the corresponding halide compounds are formed.
His work included investigations of osmic acid, of the ferrates, stannates, plumbates, &c., and of ozone, attempts to obtain free fluorine by the electrolysis of fused fluorides, and the discovery of anhydrous hydrofluoric acid and of a series of acides sulphazotes, the precise nature of which long remained a matter of discussion.
The process exhibited several disadvantages, the electrolyte had to be kept constant in composition lest either fluorine vapours should be evolved or sodium thrown down, and the raw materials had accordingly to be prepared in a pure state.
In 1886 he succeeded in obtaining the element fluorine in the free state by the electrolysis of potassium fluoride and anhydrous hydrofluoric acid at a low temperature.
For his preparation of fluorine he was awarded the Lacase prize in 1887, and in 1906 he obtained the Nobel prize for chemistry.
It combines readily with fluorine, chlorine and bromine, and also with sulphur, selenium, phosphorus, &c.
Manganic Fluoride, MnF3, a solid obtained by the action of fluorine on manganous chloride, is decomposed by heat into manganous fluoride and fluorine.
It combines with fluorine with incandescence at ordinary temperatures, and with chlorine at 250-300°; carbon, silicon, and boron, when heated with it in the electric furnace, give crystals harder than the ruby.
The term is applied to the four elements fluorine, chlorine, bromine and iodine, on account of the great similarity of their sodium salts to ordinary sea-salt.
Thus, as the atomic weight increases, the state of aggregation changes from that of a gas in the case of fluorine and chlorine, to that of a liquid (bromine) and finally to that of the solid (iodine); at the same time the melting and boiling points rise with increasing atomic weights.
All four of the halogens unite with hydrogen, but the affinity for hydrogen decreases as the atomic weight increases, hydrogen and fluorine uniting explosively at very low temperatures and in the dark, whilst hydrogen and iodine unite only at high temperatures, and even then the resulting compound is very readily decomposed by heat.
Compounds of fluorine and oxygen, and of bromine and oxygen, have not yet been isolated.
In some respects there is a very marked difference between fluorine and the other members of the group, for, whilst sodium chloride, bromide and iodide are readily soluble in water, sodium fluoride is much less soluble; again, silver chloride, bromide and iodide are practically insoluble in water, whilst, on the other hand, silver fluoride is appreciably soluble in water.
Again, fluorine shows a great tendency to form double salts, which have no counterpart among the compounds formed by the other members of the family.
In France it is called fluorine, whilst the term fluor is applied to the element (F).
In both cases the spar evolves free fluorine, which ozonizes the air.
In the spring of 1813 he was engaged on the chemistry of fluorine, and though he failed to isolate the element, he reached accurate conclusions regarding its nature and properties.
Selenium combines directly with hydrogen when heated in the gas, and with fluorine in the cold.
Selenium fluoride, SeF4, is obtained as a colourless liquid by the direct action of fluorine or selenium (P. Lebeau, Comptes rendus, 1907, 144, p. 1042).
It does not dissociate on heating as do the pentachloride and pentabromide, thus indicating the existence of pentavalent phosphorus in a gaseous compound; dissociation, however, into the trifluoride and free fluorine may be brought about by induction sparks of 150 to 200 mm.
Baker), and when this is not so, indirect methods are available, except with bromine and fluorine (and also with the so-called inert gases - argon, helium, &c.), which so far have yielded no oxides.
Fluorine and its compounds are often supposed to have been among the agencies which produce this change, but more probably carbonic acid played the principal role.
Rend., 1900, 130, p. 865) by fractionally distilling the product formed in the direct action of fluorine on sulphur.