Since ClO3 is a polyatomic atom (chlorate ion) with a charge of -1 it is represented with 1 chlorine atom and 3 oxygen atoms. The chlorine atom has two double bonds with two oxygen atoms and a single bond with the last oxygen atom.
Remember to put square brackets around the lewis dot structure to indicate it is a polyatomic atom and add a negative sign to indicate its charge!The atom has a charge of -1 due to there being 26 electrons in its structure even though oxygen only has 6 valence electrons (3 oxygen atoms have 18) and chlorine has 7 valence electronics, which makes a total of 25 valence electrons in the atoms themselves. This means that the polyatomic atom needs an extra electron to have atoms with stable octet valence shells causing a negative charge of 1.
