These hydroxides evolve a large amount of heat when dissolved in water. Hydroxides which are formed by the reaction of oxide and water are white colored crystalline solids. In pure state oxides and peroxides are colorless. Superoxides are either yellow or orange in color and paramagnetic in nature. Stability of oxides increases as the size of the metal ion increases. General Characteristics of the Compounds of the Alkali MetalsĪlkali metals form monoxide, peroxide and superoxide. Note - Alkali metals form deep blue colored paramagnetic solutions with ammonia. M + (dissolved in ammonia) + e - + NH 3 □ MNH 2 + 1/2H 2 On standing, this solution slowly releases H 2 and forms amide. Note – Li is the most powerful while Na is the least powerful reducing agent among alkali metals.Īll alkali metals can be dissolved in liquid ammonia. (all alkali metals can reduce water to produce hydrogen gas) Note – LiI is most covalent in nature because lithium ion has high polarization capability and is small in size.Īll alkali metals are strong reducing agents. They react vigorously and rapidly with halogens and form ionic halides. Note – Li reacts with H 2 at 1073K temperature.Īlkali metal hydrides show high melting points as they are ionic solids. They react with dihydrogen and forms their respective hydrides. Note – Li is a small size alkali metal with very high hydration energy, so it reacts less vigorously with water. They easily react with water and form hydroxide and hydrogen. Note – Alkali metals are highly reactive towards oxygen and water, so they are generally kept in kerosene. M + O 2 □ MO 2 (Superoxide, where M = K, Rb, Cs) These oxides react with moisture and form hydroxides. Elements of the First Group – Chemical PropertiesĪlkali metals react with air and form their oxides.
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