ClO2- ion
chlorine has 7 valence electrons and oxygen has 2 valence electrons
7+6(2)+1=20 total we have 20 valece electrons
formal charge =valence electrons-non valence bonding electrons=bonding electrons/2
therefore for cl=7-4=4/2=+1
o=6-6-2/2=-1
0=6-4-4/2=0 please check the attachment
