Question

What are the common physical and chemical features of alkali metals ?

Answer 1

$\text{Physical Properties}$

1. The alkali metal is soft so we can cut them easily, we can able to cut the sodium metal even by using the knife

2. Generally the alkali metal is lightly coloured and mostly they appear as silvery white

3. Alkali metal is weak in metallic bonding and so they are having low boiling point and melting point.

4. Metals like K and Cs losses electrons when they get irradiated with light and also displays Photoelectric effect

$\text{Chemical Properties}$

1. Alkali metals react with water and forms oxide and hydroxide so the reaction will be more spontaneous while moving down the group.

2. Alkali metal reacts with water and forms dihydrogen and hydroxides.

$2M+2H_{2}O\to 2M^{+}+2O{H}^{-}+H_2$

3. Dihydrogen reacts with alkali metals and forms metal hydrides. The hydrides have higher melting points and they are solids which are ionic.

$2M+H_2\to 2MH$

4. Alkali metals directly reacts with halogens and forms ionic halides except Li.

$2M+C{l}_2\to 2MCl$

5. When alkali metals got dissolved in liquid ammonia, it result in blue coloured solution which are naturally conducting.