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o Calcium, strontium and barium react with hydrogen to form metallic hydrides., , Metallic hydrides give hydrides ions., M+H2 = 2MH2 = M*+2H™, , o Hydrides react violently with water to release hydrogen. Calcium hydride, called “Hydrolith” is used for producing hydrogen., , CaH2+2H20 — Ca(OH)2+ He, , 4.Carbides, , o Alkaline earth metals and their oxides, except beryllium, react with, carbon to yield carbides. Carbides react with water to, liberate acetylene gas and hence used as a source for the gas., , M + 2C =~ MC2, MC2 + 2H20 = M(OH)2 + C2H2, , 5.Carbonates and Bicarbonates, , °, , The hydroxides react with carbon dioxide to carbonates., M(OH)2+CO2 = MCOs+H20, Bicarbonates are soluble in water and exist only in solution., , °, , °, , Carbonates exist as solid and insoluble in water. The solubility of, carbonates decreases from Be to Ba., , °, , In the presence of carbon dioxide, carbonates dissolve by, forming bicarbonates., , °, , lonic character and the thermal stability of the carbonates, increases from Be to Ba., , 6.Reaction with Halogens- Formation of Halides, , o Alkaline earth metals from calcium to barium react with all halogens, to form solid ionic halides with a definite crystal structure. Reactivity, decreases from fluorine to iodine., , °, , Beryllium halides are an exception with more covalent, , bonding because of the high polarization of the small covalent ion, on the electron cloud of the halogen anion as indicated by, , the Fajan’s rule., , °, , In the gas phase, Beryllium halides exist as individual molecules and, in the solid phase, they form chains of Be-x., , SS, Cee, i ww NN, , Halides of Alkaline Earth Metals, , Fluorides are insoluble in water. The solubility of other halides, increases with increase in ionic size i.e. from Mg” to Ba’., , °, , °, , Halides are hygroscopic and have the water of crystallization in their, solid state (CaCl2.6H20). Fused halides are used as dehydrating, agents.