Chemistry : general, medical, and pharmaceutical including the chemistry of the British pharmacopœia / by John Attfield.

  • John Attfield
Date:
1869
Catalogue details

Licence: Public Domain Mark

Credit: Chemistry : general, medical, and pharmaceutical including the chemistry of the British pharmacopœia / by John Attfield. Source: Wellcome Collection.

    49/650 (page 33)
    it will displace two atoms of hydrogen, or combine with the same number; nitrogen is usually trivalent (triv'-a-lent; from tres, three, and valens); and carbon quad-riv'-a-lent (from quatuor,four, or quater, four times, and valens). Chlorine, iodine, and bro- mine, as well as potassium, sodium, and silver among the metals, are, like hydrogen, univalent (u-niv'-a-lent; from uni and valens). Earium, strontium, calcium, magnesium, zinc, cadmium, mercury, and copper, like oxygen, are bivalent. Phosphorus, arsenicum, antimony, and bismuth, like nitrogen, usually exhibit trivalent properties; but the composition of certain compounds of these elements shows that the several atoms are sometimes quinquivalent (quin-quiv'-a-lent; quinquies, five times, and valens). Gold and boron are trivalent. Silicon (the characteristic element of flint and sand), tin, aluminium, platinum, and lead resemble carbon in being quadrivalent. Sulphur, chromium, manganese, iron, cobalt, and nickel are sexivalent (sex-iv'-a-lent; from sex, six, or sexies, six times, and valens), but frequently exert only bivalent, trivalent, or quadrivalent activity. This quantivalence (quant-iv'- a-lence ; from quantitas, quantity, and valens), also somewhat ob- scurely termed atomicity, dynamicity, and equivalence of elements, may be ascertained at any time on referring to the Table of the Elements at the end of this volume, where Roman numerals, i, II, III, IV, V, VI, are attached to the symbols of each element to indicate atomic univalence, bivalence, trivalence, quadrivalence, quinquivalence, or sexivalence. Dashes (H', 0, W) similar to those used in accentuating words are often used instead of figures in expressing quantivalence. The quantivalence of elements, as they one after another come under notice, should be carefully committed to memory; for the composition of com- pounds can often be thereby predicated with accuracy, and re- membered with ease. For instance, the hydrogen compounds of chlorine, CI', oxygen, 0, nitrogen, W, and carbon, Q, will be respectively H'Cl', H'^O, H'^K', and H'^C,—one univalent atom, H', balancing or saturating one univalent atom, CI'; two univalent atoms, H'^, and one bivalent atom, 0, saturating each other; three univalent atoms, H'g, and one atom having trivalent activity, W, saturating each other; and four univalent atoms, H^, and one quadrivalent atom, C, saturating each other. Carbonic acid gas, C^^O^? again, is a saturated molecule con- taining one quadrivalent and two bivalent atoms. The doctrine of quantivalence will again be mentioned after the first six metals have been studied, when abundant illustrations of its applications will have occurred. c5