Word Finder - halogen

definition

Any element of group 17, i.e. fluorine, chlorine, bromine, iodine and astatine, which form a salt by direct union with a metal.

definition

A light fixture in which the filament is surrounded by an atmosphere of a halogen gas,

It is decomposed by the halogen elements and also by sulphuretted hydrogen.

This change only occurs when the halogen atom is in the orthoor paraposition to the - N2 - group.

Molybdenum combines with the halogen elements in varying proportions, forming with chlorine a di-, tri-, tetraand penta-chloride, and similar compounds with bromine and iodine.

Similarly, the formation of organic halogen products may be effected by electrolytic chlorine, as, for example, in the production of chloral by the gradual introduction of alcohol into an anode cell in which the electrolyte is a strong solution of potassium chloride.

It is to be noted that only traces of the aromatic amines are produced by heating the halogen substituted benzenes with ammonia, unless the amino group be situated in the side chain, as in the case of benzylamine.

In formulating these facts Liebig at first retained the dualistic conception of the structure of acids; but he shortly afterwards perceived that this view lacked generality since the halogen acids, which contained no oxygen but yet formed salts exactly similar in properties to those containing oxygen, could not be so regarded.

The amino derivatives are stable bases which readily yield substitution derivatives when acted upon by the halogen elements.

The same absorbent' quantitatively takes up any halogen and sulphur which may be present.

Halogen acids convert it into monohalogen fatty acids, and the halogens themselves convert it into dihalogen fatty acids.

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.

We may, in fact, consider that the descriptive study of the various halogen compounds dates from about this time.

Of the halogen compounds of phosphorus, the trichloride was discovered by Gay Lussac and Thenard, while the pentachloride was obtained by Davy.

The oxychloride, bromides, and other compounds were subsequently discovered; here we need only notice Moissan's preparation of the trifluoride and Thorpe's discovery of the pentafluoride, a compound of especial note, for it volatilizes unchanged, giving a vapour of normal density and so demonstrating the stability of a pentavalent phosphorus compound (the pentachloride and pentabromide dissociate into a molecule of the halogen element and phosphorus trichoride).

From the fact that reduction products containing either one or two double linkages behave exactly as unsaturated aliphatic compounds, being readily reduced or oxidized, and combining with the halogen elements and haloid acids, it seems probable that in benzenoid compounds the fourth valencies are symmetrically distributed in such a manner as to induce a peculiar stability in the molecule.

By actual observations it has been shown that ether, alcohol, many esters of the normal alcohols and fatty acids, benzene, and its halogen substitution products, have critical constants agreeing with this originally empirical law, due to Sydney Young and Thomas; acetic acid behaves abnormally, pointing to associated molecules at the critical point.

The same difference attends the introduction of the methyl group into many classes of compounds, for example, the paraffins, olefines, acetylenes, aromatic hydrocarbons, alcohols, aldehydes, ketones and esters, while a slightly lower value (157.1) is found in the case of the halogen compounds, nitriles, amines, acids, ethers, sulphides and nitro compounds.

It is remarkable that the position of the halogen in the molecule has no effect on the heat of formation; for example, chlorpropylene and allylchloride, and also ethylene dichloride and ethylidene dichloride, have equal heats of formation.

An important nucleus-synthetic reaction is the saponification of nitriles, which may be obtained by the interaction of potassium cyanide with a halogen substitution derivative or a sulphonic acid.

The advantage of the new definition lies in the fact that the estimation of the chlorine (or rather of the total halogen expressed as chlorine) is sufficient to determine the salinity by a very simple operation.

Eltekow, Ber., 1878, 11, p. 414); by the action of metals on the halogen compounds Cn.H 20 Br 2 i by boiling the aqueous solution of nitrites of the primary amines (V.

Grignard (Comptes rendus, 1900 et seq.) observed that magnesium and alkyl or aryl halides combined together in presence of anhydrous ether at ordinary R temperatures (with the appearance of brisk boiling) to form compounds of the type RMgX(R = an alkyl or aryl group and X = halogen).

Chlor-, brom-, iodoand fluor-benzoic acids are known and can be obtained by oxidizing the corresponding halogen toluenes, or from the amido acids, or by substitution.

Nickel occludes hydrogen readily, is attacked by the halogen elements, and oxidizes easily when heated in air.

The word halogen is derived from the Greek as (sea-salt) and yevvav (to produce), and consequently means the sea-salt producer.

The halogen of lower atomic weight can displace one of higher atomic weight from its hydrogen compound, or from the salt derived from such hydrogen compound, while, on the other hand, the halogen of higher atomic weight can displace that of lower atomic weight, from the halogen oxy-acids and their salts; thus iodine will liberate chlorine from potassium chlorate and also from perchloric acid.

The ketenes are usually obtained by the action of zinc on ethereal or ethyl acetate solutions of halogen substituted acid chlorides or bromides.

Compounds of antimony with all the halogen elements are known, one atom of the metal combining with three or five atoms of the halogen, except in the case of bromine, where only the tribromide is known.

It receives application in synthetic organic chemistry by virtue of its power to remove the halogen atoms from alkyl haloids, and so effect the combination of the two alkyl residues.

The tertiary phosphines are characterized by their readiness to pass into derivatives containing pentavalent phosphorus, and consequently they form addition compounds with sulphur, carbon bisulphide, chlorine, bromine, the halogen acids and the alkyl halides with great readiness.

The formation of addition compounds with the halogens, halogen hydrides, and with nitrosyl chloride, is characteristic of many, whilst others unite readily with nitrogen peroxide.

The haloid esters of the paraffin alcohols formed by heating the alcohols with the halogen acids are the monohaloid derivatives of the paraffins, and are more conveniently prepared by the action of the phosphorous haloid on the alcohol.

They do not possess basic properties; the halogen in the chlorine compounds is readily replaced by oxygen, and the oxides produced behave like basic oxides.

In its properties it shows some analogy to the halogen acids, since it forms difficultly soluble lead, silver and mercurous salts.

I have been running with halogen bulbs in my tail lights for about 12 years now.

The Cooking Pot has a solid base and is suitable for heating on all hobs, including ceramic and halogen cookers.

Internally the house benefits from brass halogen down lights throughout, and these are matched by brass dimmer switches and all electrical sockets.

This in turn involves bond dissociation, gain of an electron by the halogen, and hydration of the halide ion.

The site was lit by four halogen floodlights at the corners, an echo of the original guard towers of the PoW camp.

An aryl halide has a halogen atom attached directly to a benzene ring.

The ceiling is coved with recessed halogen down lights and there is a window above the sink overlooking the rear patio and garden.

Options are also available for fire retardant formulas including low smoke zero halogen.

A more reactive halogen can displace a less reactive halogen from an aqueous solution of its salt.

All you would need to do is swap the symbol Cl in the two equations for whichever other halogen you were interested in.

A tungsten halogen source may be better with auto white balance.

I am going to attempt this, for the first time ever, with a 500 watt quartz halogen bulb!

Don't confuse low energy bulbs with low voltage halogen light bulbs.

Inset four ring halogen hob with extractor hood over.

The average low beam range of a regular halogen headlamp is approximately 40 meters.

The 612 Scaglietti's twin xenon projector headlights also offer a beam that is far superior to traditional halogen lights.

The test car was also fitted with optional adaptive halogen headlights, which see round corners for a worthwhile £ 250.