Since ClO3 is a polyatomic atom (chlorate ion) with a charge of -1 it's far represented with 1 chlorine atom and three oxygen atoms. The chlorine atom has two double bonds with two oxygen atoms and an unmarried bond with the last oxygen atom.
Here is a comic of the structure (please pardon the terrible drawing):
Remember to position rectangular brackets across the Lewis dot shape to signify it is a polyatomic atom and upload a terrible signal to signify its charge!
The atom has a charge of -1 because there are 26 electrons in its structure even though oxygen has 6 valence electrons (three oxygen atoms have 18) and chlorine has 7 valence electronics, which makes a complete of 25 valence electrons inside the atoms themselves. This way the polyatomic atom needs a further electron to have atoms with stable octet valence shells inflicting a negative fee of one.