The most common type of exception to the octet rule are compounds or ions with central atoms

Question:

The most common type of exception to the octet rule are compounds or ions with central atoms having more than eight electrons around them. PF5, SF4, ClF3, and Br3- are examples of this type of exception. Draw the Lewis structures for these compounds or ions. Which elements, when they have to, can have more than eight electrons around them? How is this rationalized?