Question

Does a chlorate ion have resonance structures?

Answer 1

Yes, the chlorate ion has three major contributors to the resonance hybrid.

We can write three important equivalent Lewis structures for the chlorate ion. See this diagram from http://www.austincc.edu/lgregory/Lewis%20Diagram%20polyatomic%20answers.htm

There are other Lewis structures, but they are less important.

Each of the three structures is a resonance contributor.

The structure of the resonance hybrid is

The negative charge is distributed equally among the three O atoms.