Appearance, and Many phos- Ca(PO3)2 with Soft wax-like general physical solid. properties. General chemical properties. 425 Crystalline. of Non-conductor Burns in air to Does not form 13.2 ⚫083 As2O3 and Grey, hard, Fair conductor Burns in air to No salts known 18 ⚫053 Chief naturally not determined. ⚫0308 Bismuth is found native; also BigOg. and BigSg, &c., but not in large quantities. Metal not yet Prepared by obtained. heating Biog Oxide, Er20g, is with charcoal. Grey, with faintly reddish tinge; crystallises easily; brittle. Bad conductor of electricity. Burns in air to Bi203 Combines directly with Cl, Br, and I. Oxidised by HNO3, and at same time Bi.3NOg is formed. Many salts known derived from acids. No hydride known. Oxides are basic; Bi205 shews very slight acidic functions. Atom trivalent in gaseous molecules. General formulae and chemical characters of compounds of elements of Group V. Hydrides. MH; M = N, P, As, Sb. Oxides. MO; M=N, V. M,O,; M = N, V, Nb, Bi. group except Er. Hydrates of many of these oxides are known. Sulphides. No sulphides of niobium or erbium have yet been prepared. M,S,; M = any element of the group except N, Ta, (Nb or Er). M,S,; MP, V, As, Sb. A few other sulphides are known, e.g. NS,, Ta,S. Haloid compounds. No haloid compounds of erbium have yet been prepared; the haloid compounds of nitrogen are very unstable and explode with great violence, their composition is still doubtful. MX,; M = any element of the group except Ta (? N) or Er. Acids. The following are the chief compounds of hydrogen with oxygen and an element of Group V. which are acids (when Aq is added to a formula it indicates that the acid is known only in aqueous solution). 2 HNOAq, HNO,Aq, HNO,. H,PO,Aq, H.PO,Aq, H.PO,, HPO, HP,O,, HVO, HVO HASO,Aq, HASO HASO, HAS,O HSbO, Hsbo, HSbo, HSbO H Ta2O 2 Salts. The only elements of the group which are known to form series of definite salts by replacing the hydrogen of acids are vanadium, didymium, erbium, and bismuth. The salts of vanadium are all basic salts, they belong for the most part to the series VOX and (VO),X,; the salts of didymium and erbium belong to the series M,3X; the normal salts of bismuth belong to the series Bi̟,3X, but besides these a great many basic salts exist. (X=SO, 2NO,, &c.). Antimony forms a few compounds which may be regarded as basic salts, especially aSb,O,.ySO, and xSb,O,.yN,O,; tartar-emetic, KSbCHO,, is probably to be classed as a double antimonypotassium salt. ვი 3 39 39 The following are the principal compounds of elements of 426 Group V. which have been gasified, and the relative densities of the vapours of which have been determined; NH, PH, ASH, PC, PI, PF,, VCI, AsCl, AsI, NbCl,, SbCl, Sb, TaCl, BiCl. The statements made in the table in par. 424 regarding the valencies of the atoms of the elements of Group V. are based on the existence and compositions of these gaseous molecules. Arsenious and antimonious oxides have been gasified; the 427 compositions of the gaseous molecules of these compounds are expressed by the formulae As,O, and Sb. The formulae of the following oxides of nitrogen are molecular NO, NO, NO, NO. A few oxychlorides, e.g. NbOCl,, have also been gasified. The formulae of the other compounds are not necessarily molecular; they are the simplest formulae that can be given, consistently with the determined values of the atomic weights of the elements, and with the reactions of the compounds. The hydrides MH, are gases under ordinary conditions. Ammonia, NH, is obtained in small quantities by the direct union of nitrogen and hydrogen under the influence of the induced electric discharge; also in many reactions in which hydrogen is produced in contact with nitrogen, e.g. when steam and nitrogen are passed over hot iron, or when nitrogen is produced in contact with hydrogen, e.g. when hydrogen and nitric oxide are passed over hot finely divided platinum. Ammonia is usually prepared by heating a mixture of ammonium chloride and lime; 2NH C1+CaO= CaCl,+H,O + 2NH. 4 Phosphoretted hydrogen or phosphine, PH,, may be obtained by heating a mixture of phosphonium iodide and an alkali; PH,I + KOHAq = KIAq+ H2O + PH,; it is however more usually prepared by heating a solution of an alkali with phosphorus; 3KOHAq + 3H ̧0 + 4P = 3KH,Pо ̧Aq + PH (potassium hypophosphite remains in solution, phosphine is evolved as a gas). Arsenuretted hydrogen or arsine, AsH,, is obtained by producing hydrogen in contact with a solution of an arsenic compound. Antimonuretted hydrogen, or stibine, SbH,, is obtained by a similar method. Thus, = M ̧О ̧Aq+жM ̧O̟ ̧Aq+12H+xH=2MH ̧+3H2O+H+xM ̧O̟ ̧Aq The hydrides MH, can be oxidised to oxides and water; ammonia is oxidised by mixing it with much oxygen and bringing a flame to the mixture; water, nitrogen, and a little ammonium nitrate (NH,NO) are formed; phosphine is oxidised to phosphorus pentoxide (PO) and water by mixing it with air or oxygen and raising the temperature; arsine and stibine are oxidised by mixing with air or oxygen and bringing a flame to the mixture; if much oxygen is present the products are water and arsenious or antimonious oxide; if little oxygen is present, water, arsenic or antimony, and a little arsenious or antimonious oxide, are formed. Arsine and stibine are decomposed by heat; ammonia and phosphine are much more stable towards heat. The most important and best studied oxides of the 428 elements of Group V. are those whose composition is expressed by the formulae M,O, and M,O,, respectively. 2 3 2 3 3 2 The trioxides MO, may be formed by the direct union of their elements; Nь ̧О, and Ta2O, have not yet been prepared, and as erbium has not been isolated it is uncertain whether the oxide Er.O, would or would not be formed by heating erbium in oxygen. Nitrogen and oxygen combine only when a mixture of the gases is submitted to the continued action of electric sparks, and then only a small quantity of NO is formed; the other elements of the group are readily oxidised to M,O, by heating in air or oxygen. 3 3 2 3 3 39 The oxides MO, may be divided into three classes: (1) acidic oxides, NO, PO; (2) basic oxides, Di̟O, Er.O, Bi,O,; (3) oxides which are both acidic and basic, As,O,, SbO, (?V2O). The oxides NO, and P2O, dissolve in water to form solutions of nitrous acid HNO,, and phosphorous acid H.PO,7 respectively; neither oxide shews the smallest tendency to interact with acids and form salts. The oxides Di,O,, Er,O, and BiO interact with acids to produce salts; they are all insoluble in, and unchanged by contact with, water. Arsenious oxide, AsO, dissolves in water and the solution interacts with caustic soda or potash to form salts of the composition MASO, (M = Na or K); but no oxyacid derived from As,O, has been obtained. Antimonious oxide, Sb,O,, is slightly soluble in water and the solution reacts with potash or soda to form antimonites M,SbO,; the acid H.SbO, is known as a solid, but it is not obtained by the direct interaction of water with Sb,O,. Arsenious oxide interacts with concentrated hydrochloric acid to form arsenious chloride, AsCl,; it is also said to form a salt AsKCHO, by reacting with solution of potassiumhydrogen tartrate; antimonious oxide forms SbCl, by reacting 2 3 M. E. C. 20 429 with concentrated hydrochloric acid, it forms SbKC,H,O, by dissolving in KHCH ̧O.Aq and crystallising, and it probably interacts with concentrated sulphuric acid to form Sb,(SO). Vanadium trioxide V2O, is said to interact with acids to produce a series of unstable, easily oxidised, salts. 3 The pentoxides, M,O,, can be obtained by heating the elements in oxygen when M = P, V, Nb, or Ta; by evolving oxygen in contact with M.O, when M = As, Sb, Di, or Bi; and by withdrawing water from nitric acid in the case of NO, (2HNO, - H ̧O – N ̧O.). 2 4 2 2 7 2 5 5 = 2 The oxides NO, and P2O, dissolve in water to form acid solutions from which the acids HNO, (from N,O,), HPO, H.PO, and HP,O, (from P2O.) can be obtained. The oxides As O, and Sb,O, are slightly soluble in water forming acid solutions from which salts can be obtained, e.g. Ag AsO,, KSbO3; V O, is scarcely soluble, Nb,O, TaO, Di̟O., and Bi̟0 are insoluble, in water; salts of the forms MVO,, MTaO, and M Nb2O, &c. are obtained by heating the pentoxides of V, Ta, and Nb, with molten potash or soda; no salts derived from Di2O, or Bi2O, are known; Bi,O, however dissolves in much molten potash and possibly forms very easily decomposed salts. 7 5 5 37 5 Of the remaining oxides, nitrous oxide NO, nitric oxide NO, nitrogen dioxide NO,, and nitrogen tetroxide NO, are gases; they are all obtainable by reactions between aqueous solutions of nitric acid and various reducing agents; the oxide NO, exists at moderately high temperatures, when this oxide is cooled it becomes very dark reddish black in colour and the vapour density now shews that its molecular composition is expressed by the formula NO. All the oxides of nitrogen are acidic; none shews any basic properties. The haloid compounds are generally obtained by the direct union of their elements; also in many cases by dissolving the trioxides, M,O,, in haloid acid and evaporating. Those elements of the group which form pentachlorides MCl are P, Nb, Sb, and Ta; the compounds MCI, are produced by heating these elements in excess of chlorine. Trichlorides MC, are formed by heating arsenic or bismuth in chlorine; vanadium heated in a stream of chlorine forms the tetrachloride VCI. Pentahaloid compounds (MX) of nitrogen, vanadium, arsenic, didymium, and bismuth, have not yet been obtained; no trihaloid compound (MX) of tantalum is known; haloid compounds of erbium have not as yet been isolated. Vanadium |