In order to write lewis structure of any molecule or ion we follow the simples steps
i) Identify the central atom
ii) Sum total the number of valence electrons on each atom in the molecule or ion.
iii) Arrange a pair of electrons in between two atoms to show a single bond between them
iv) Give rest electrons to the atoms to fulfill its octet (in case of hydrogen we go for two electrons only), if sufficient electrons are available
so the lewis structure of chlorous acid will be
Formal charge
Formal charge=[No.of valence electrons]- [No.of non bonded electrons]-[ (No of bonded electrons)/2]
a) on oxygen : -1
b) chlorine : +1
c) hydrogen : 0
