Lewis Dot of the Chlorate Ion
Chlorine does not follow the octet rule. It will hold more than 8 electrons.
Chlorine having valence electrons in the 3rd energy level, will also have access to the 3d sublevel, thus allowing for more than 8 electrons.
Elements in the first 2 periods of the Periodic Table do not have access to the d sublevel and must adhere to the octet (or duet H and He) rule.
Lewis Dots structure.
All the bonds are the same length and must be thought of as a hybrid of multiple resonance structures.