Cryolite ( ${\mathbf{Na}}_3{\mathbf{AlF}}_6$) is an indispensable component in the electrochemical manufacture of aluminium. Draw a Lewis structure for the ${{\mathbf{AlF}}_6}^{3-}$ion.

A Lewis structure can be defined as the basic structure of a molecule that used the valence electron of each atom involved.In Lewis’s structure, the smallest amountof electronegative atom is going to be the central atom.

Formal Charge is a theoretical concept that is also called fake charge. It is the charge which is dispersed on the whole molecule, not on the single atom.

Formal Charge = Valence electron – Lone pair electron – ½ (Bonded electron)

The octet rule may be defined as the maximum of 8 electronsthat can be filled in an orbital of an atom. It can be completed by sharing or giving the electrons to become stable.

Al-atom belongs to group 13having 3electrons in the valence shell and requiring 5 electrons to fulfill its octet whereasF-atom belongs to group 17 having 7electrons in the valence shell and requiring1 electron to fulfill its octet. The Al-atom can be bonded with F-atom and havea single bond and form an octahedral structure.