(i) Reaction with air and water: are almost inert to air and water because of the formation of oxide layer on their surface.
(a) Powdered burns in air to form and.
(b) , being more electropositive, burns in air with a dazzling sparkle to form and .
(c) and react readily with air to form respective oxides and nitrides.
(d) react vigorously even with cold water.
(ii) Alkaline earth metals react with halogens at high temperatures to form halides.
(iii) All the alkaline earth metals, except Be, react with hydrogen to form hydrides.
(iv) They react readily with acids to form salts and liberate hydrogen gas.
(v) They are strong reducing agents. However, their reducing power is less than that of alkali metals. As we move down the group, the reducing power increases.
(Vi) Similar to alkali metals, the alkaline earth metals also dissolve in liquid ammonia to give deep blue coloured solutions.
Q: 3. Why are alkali metals not found in nature?
Alkali metals include lithium, sodium, potassium, rubidium, cesium, and francium. These metals have only one electron in their valence shell, which they lose easily, owing to their low ionization energies. Therefore, alkali metals are highly reactive and are not found in nature in their elemental state.
Q: 4. Find the oxidation state of sodium in.
Let the oxidation state of be. The oxidation state of oxygen, in case of peroxides, is
Therefore, the oxidation sate of sodium is
Q: 5. Explain why is sodium less reactive than potassium?
In alkali metals, on moving down the group, the atomic size increases and the effective nuclear charge decreases. Because of these factors, the outermost electron in potassium can be lost easily as compared to sodium. Hence, potassium is more reactive than sodium.