Which of the following solids is polymeric ?

Options

A. `BaCI_(2)`
B. `CaCI_(2)`
C. `BeCI_(2)`
D. `MgCI_(2)`

Answer

C

Explanation

The anhydrous halides of Be are polymeric. Theh polymeric structre of `BeCl_(2)` is due to the electron dificient nature of Be as it has only `4e^(-)`s in thhe valence shell. Thus, it can accept two electron pairs (from neighboring Cl atoms forming coordinate covalent bonds) to complete the octet. Thus, in the polymeric chain, each Be is tetrahedrally surrounded by 4 chlorine atoms. two of te Cl atoms are attached by covalent bonds while thhe other two by coordinate covalents bonds.
Through the structure of the `(BeCl_(2))_(n)` polymer is similar to that for `(BeH_(2))_(n)`, the bonding is different. bothh show clustering but the hydrode has 3-center bonding, while the halides have halogen bridges, in which a Cl atom bonded to one Be atom uses a lone pair of `e^(-)` to form a coordinated bond to another be atom