Draw Lewis structures of all the important resonance forms of (a) ${{\mathbf{HCO}}_2}^{-}$ (H is attached to C); (b) ${\mathbf{HBrO}}_4\left({\mathbf{HOBrO}}_3\right)$

A Lewis structure can be defined as the basic structure of a molecule which used the valence electron of each atom involved. In Lewis’s structure, the least electronegative atom will be the central atom.

C belongs to group 14 having 4 electrons in the valence required to give or take 4 electrons to fulfil its octet, O-atom belongs to group 16 having 6 electrons in the valence shell and requires 2 electrons to fulfil the octet. In Lewis’s structure, the C-atom needs 4 electrons which will be provided by the other 2 O-atom and 1 H-atom. There is a movement of negative charge over O-atom.

Br belongs to group 17 having 7 electrons in the valence required to give or take 1 electron to fulfil its octet, O-atom belongs to group 16 having 6 electrons in the valence shell and requires 2 electrons to fulfil octet. In Lewis structure, the Br-atom need 1 electron which will be provided by the O-atom. There is 4 O-atom bonded to the Br-atom and have electron more than its octet which was balanced by the movement of electron on the O-atom.