composed of two elements; e.g. common salt, which is a compound of sodium and chlorine. Its symbol is NaCl, its chemical name sodium chloride. The ending ide is applied to the last name of binaries. How many parts by weight of Na and of Cl in NaCl? What is the molecular weight, i.e. the weight of its molecule? Name KCl. How many atoms in its molecule? Parts by weight of each element? Molecular weight? Does the symbol stand for more than one molecule? How many molecules in 4 NaCl? How many atoms of Na and of Cl? Name these: HCl, NaBr, NaI, KBr, AgCl, AgI, HBr, HI, HF, HgO, ZnO, ZnS, MgO, CaO. Compute the proportion by weight of each element in the last three.
A coefficient before the symbol of a compound includes all the elements of the symbol, and shows the number of molecules. How many in these: 6 KBr? 3 Sn0? 12 NaCl? How many atoms of each element in the above?
An exponent, always written below, applies only to the element after which it is written, and shows the number of atoms. Explain these: AuCl3, ZnCl2, Hg2Cl2.
Write symbols for four molecules of sodium bromide, one of silver iodide (always omit coefficient one), eight of potassium bromide, ten of hydrogen chloride; also for one molecule of each of these: hydrogen fluoride, potassium iodide, silver chloride.
In all the above cases the elements have united atom for atom. Some elements will not so unite. In CaCl2 how many atoms of each element? Parts by weight of each? Give molecular weight. Is the size of the molecule thereby changed? Name these, give the number of atoms of each element in the molecule, and the proportion by weight, also their molecular weights: AuCl3, ZnCl2, MnCl2, Na2O, K2S, H3P, H4C.
Principal Elements. Name. Sym. At. Wt. Valence. Vap.D. At.Vol. Mol.Vol. State. Aluminium Al 27. II, IV ... ... ... Solid Antimony Sb 120. III, V. ... ... ... " Arsenic As 75. III, V 150. " Barium Ba 137. II ... ... ... " Bismuth Bi 210. III, V ... ... ... " Boron B 11. III ... ... ... " Bromine Br 80. I, (V) 80. Liquid Cadmium Cd 112. II 56. Solid Calcium Ca 40. II ... ... ... " Carbon C 12. (II), IV ... ... ... " Chlorine Cl 35.5 I, (V) 35.5 Gas Chromium Cr 52. (II),IV,VI ... ... ... Solid Cobalt Co 59. II, IV ... ... ... Gas Copper Cu 63. I, II ... ... ... " Fluorine F 19. I, (V) ... ... ... Gas Gold Au 196. (I), III ... ... ... Solid Hydrogen H 1. I 1. Gas Iodine I 127. I, (V) 127. ... ... Solid Iron Fe 56. II,IV,(VI) ... ... ... " Lead Pb 206. II, IV ... ... ... " Lithium Li 7. I ... ... ... " Magnesium Mg 24. II ... ... ... " Manganese Mn 55. II, IV, VI ... ... ... " Mercury Hg 200. I, II 100. Liquid Nickel Ni 59. II, IV ... ... ... Solid Nitrogen N 14. (I),III,V 14. Gas Oxygen O 16. II 16. " Phosphorus P 31. (I),III, V 62. Solid Platinum Pt 197. (II), IV ... ... ... " Potassium K 39. I ... ... ... " Silicon Si 28. IV ... ... ... " Silver Ag 108. I ... ... ... " Sodium Na 23. I ... ... ... " Strontium Sr 87. II ... ... ... " Sulphur S 32. II,IV,(VI) 32(96) " Tin Sn 118. II, IV ... ... ... " Zinc Zn 65. II 32.5 "
If more than one atom of an element enters into the composition of a binary, a prefix is often used to denote the number. SO2 is called sulphur dioxide, to distinguish it from SO3, sulphur trioxide. Name these: CO2, SiO2, MnO2. The prefixes are: mono or proto, one; di or bi, two; tri or ter, three; tetra, four; pente, five; hex, six; etc. Diarsenic pentoxide is written, As2O5. Symbolize these: carbon protoxide, diphosphorus pentoxide, diphosphorus trioxide, iron disulphide, iron protosulphide. Often only the prefix of the last name is used.
16. An Oxide is a Compound of Oxygen and Some Other Element, as HgO. What is a chloride? Define sulphide, phosphide, arsenide, carbide, bromide, iodide, fluoride.
In Experiment 6, where S and Fe united, the symbol of the product was FeS. Name it. How many parts by weight of each element? What is its molecular weight? To produce FeS a chemical union took place between each atom of the Fe and of the S. We may express this reaction, i.e. chemical action, by an equation:--
Iron + Sulphur = Iron Sulphide Or, using symbols Fe + S = FeS Using atomic weights, 56 32 = 88.
These equations are explained by saying that 56 parts
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