Discuss the similarities between alkaline earth metals and gradation in the following aspects: (i) Electronic configuration.

Explanation

i) Electronic configuration:
The general electronic configuration of alkaline earth metals represented by [noble gas] `ns^2`

ii) Hydration Enthalpies:
The hydration enthalpies of alkaline earth metal ions decrease with increase in ionic size down the group
`Be^(+2) gt Mg^(+2) gt Ca^(+2) gt Sr^(+2) gt Ba^(+2)`
HYdration enthalpies of these elements ions are larger than those of alkali metal ions.
Eg: `MgCl_2 MgCl_3. 6H_2O`
`CaCl_2 CaCl_2. 6H_2O`
iii) nature of oxides and hydroxides:
Alkaline earth metals forms oxides of type MO.
These are formed by burning in oxygen
BeO is amphoteric and covalent in nature whereas other oxides are ionic and basic in nature.
Other oxides i.e., except BaO forms hydroxides with water
Eg `MgO+H_2O to Mg(OH)_2`
The solubility, thermal stability and the basic character of these hydroxides increase with increase of atomic no. from `Mg(OH)_2` to `Ba(OH)_2`
These hydroxides are less basic, less stable than alkali metal hydroxide.
`Be(OH)_2` is amphoteric in nature. This can be evidented by the following reactions
`Be(OH)_2` reacts with both acids and alkalis.
`Be(OH)_2+2OH^(-) to [Be(OH)_4]^(2-)`
Beryllation
`Be(OH)_2+2HCl+2H_2O to [Be(OH)_4]Cl_2`
Hence `Be(OH)_2` is amphoteric in nature.