Halides complex, 345 covalent, 344 ionic, 343
preparation, 342, 343 tests for, 348-350
Halogens, see separate elements Head element, 14
Helium
occurrence and isolation, 354, 355 properties, 353, 354
uses, 357 Herschel, 428
Hexafluorosilicic acid, 196 Hooker cell, 130 Hydrazine, 223, 224 Hydrazoic acid, 224, 225 Hydride ion, 89
Hydrides, 114, 115 complex, 115 interstitial, 368
Hydrogen atom, 55 atomic, 116
bonding, 43, 52-54, 57, 184, 270, 327 electrode, 97, 98
manufacture, 180 molecule, 55 non-metals, 113, 114
reactions with chlorine, 71, 72, 321 tests for, 117
Hydrogen bromide, 332, 333 Hydrogen chloride, 71, 80, 87, 88, 327
aqueous, 331 formation, 330, 331 uses, 332
Hydrogen fluoride, 53, 73, 87, 88, 114 preparation, 329
properties, 329, 330 uses, 330
Hydrogen halides, 72, 326-334 Hydrogen iodide, 321, 333, 334 Hydrogen peroxide
formation, 277 preparation, 278 properties, 279 tests, 281
uses, 281,282 Hydrogen sulphide preparation, 282
properties, 282-284 tests, 284
Hydrogencarbonates, 132-134, 183-185
INDEX 451
Hydrogensulphates, 303, 304 Hydrogensulphites. 293. 294 Hydrolysis, 45, 46, 270, 272 Hydroxylamine, 222, 223 kHypo\ 294
Ice, 53 Ilmenite, 369
Indium, 144,158
Interhalogen compounds, 345, 346 lodic(I) acid and salts, 338 lodic(V) acid and salts, 339, 340 lodic(VII) acid and salts, 342 Iodine
occurrence and extraction, 319, 320 oxides, 327
oxoacids, 337-342 properties, 310-316, 320 reactions, 320-326 tests, 349
uses, 348 Ion-exchange, 275
chromatography, 441 Ionic
bond, 28-36 lattice, 27 radius, 29, 35
lonisation energy, 15-17, 29-32, 97 Iron
chemical properties, 392, 393 complexes, 395, 397, 398 compounds, 393-397 occurrence and extraction, 391 oxidation states, 362
physical properties, 360, 361 pyrites, 261-391
refining, 392 rusting of, 398-400 tests, 400
uses, 391,392
Jeweller's rouge, 395
Kaolin, 188 Kellner-Solvay cell, 136 Kelp, 319
Kernite, 142 Kieselguhr, 186 Krypton
occurrence and isolation, 355 properties, 353, 354
uses, 357