The Theory of Valency

The Theory of Valency

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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1915 edition. Excerpt: ... Grignard's reagent, C6H6. Mg. Br, with lead dichloride at ordinary temperatures. Thus: 2 PbCL+4C6HcMgBr=Pb + Pb (C6H6)4+2 MgCl2 + 2 MgBr2 Recent research points very clearly to the fact that lead can function as a monovalent atom also. The existence of lead suboxide, Pb20, has been rendered tolerably certain by the experiments of Tanatar.1 This body, of course, might be represented by the formula Pb Pb in which the lead is clearly divalent (compare cadmium). Brislee2 has also been led to believe that lead can function as a monovalent atom by a study of the reduction of lead oxide by carbon monoxide. The experiments of Denham and Allmand3 lend further support to this view. It would seem, therefore, that the power of lead to function as a mono-, di-, and tetra-valent element has been demonstrated. The tetravalency of the last element of this group, namely thorium, is proved by the results of vapour density determinations of the tetrachloride,4 which show that its formula is TI1CI4. The hydride, ThH4, has also been isolated. The element cerium was originally placed in this group by Merideleeff, on account of its tendency to form tetravalent derivatives. The correctness of this procedure has been called into question by several chemists, who argue that cerium more properly belongs to the third group, along with aluminium and gallium, owing to the greater stability manifested by the cerous salts. Barbieri' points out, however, that it is not strictly accurate to say that the cerous salts are stable, and that the 1 Tanatar, Zeit. atwrg. Chem., 1901, 27, 304, Brislee, Trans. Chem. Soc, 1908, 93, 154. 3 Denham and Allmand, Trans. Chem. Soc., 1908, 93, 425; Denham, Trans. Chem. Soc, 1908, 93, 834. Kriiss and Nilson, Ber., 1887, 20, 1665; Troost, Compt....show more

Product details

  • Paperback | 54 pages
  • 189 x 246 x 3mm | 113g
  • Rarebooksclub.com
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 1236604539
  • 9781236604538