Explain the bond formation in `BeCl_(2) and MgCl_(2).`

Explanation

`BeCl_(2)` bond formation :
(i) ectronic eonfiguration of `Be(Z = 4)" is " " 1s^(2)2s^(2)` and electronic configuration of `Cl (Z = 17) " is " "1s^(2)2p^(6)3s^(2)3p^(5)`
(ii) Beryllium has 2 electrons in its valence shell and chlorine atoms (2) have 7 electrons in their valence shell.
(iii) By losing two electrons, Beryllium attains the inert gas configuration of Helium and becomes a dipositive cation, `Be^(2+)` ansd each chlorine atom accepts one electron to become `(Cl^(-))` uninegative anion and attains the stable electronic configuration of Argon.
(iv) Then `Be^(2+)` combine with `2Cl^(-)` ions to form an ionie crystal in which they are held together by electrostatic attractive forces.
(v) During the formation of l mole of `BeCl_(2),` the amount of energy released is - 468 kJ/mol.
This favours the formation of `BeCl_(2)` and its stabilisation.
`MgCl_(2)` bond formation:
(i) Electronic configuration of Mg `(z = 12)" is "1s^(2)2s^(2)2p^(6)3s^(2)`
Electronic configuration of `Cl (z = 17) " is "1s^(2)2s^(2)2p^(6)3s^(2)3p^(5)`
(ii) Magnesium has 2 electrons in ils valence shell and chlorine has 7 electrons in its valence shell.
(iii) By losing two electrons, magnesium attains the inert gas configuration of Neon and becomes a dipositive cation `(Mg^(2+))` and two chlorine atoms accept these electrons to become two uninegative anions `[2C1^(-)]` by attaining the stable inert gas configuration of Argon.
(iv) These ions, `Mg^(2+) and 2C1^(-)` combine to form an ionic crystal in which they are held together by electrostatic attractive forces.
(v) The energy released during the formation of I mole of `MgC1_(2)` is - 783 kJ/mole. This favours the formation of `MgCl_(2)` and its stabilisation.