Octet Rule Violators

If you look back at the general outline with which we started LDS's you will notice that we said that these ideas were “generally” true. That of course implies that they are sometimes false and, in fact, they are not always true. 

Let's look at the LDS for BH3. Following the rules above, we count electrons (6), arrange the atoms, and single bond them. However, at that point we have run out of electrons.

The Boron doesn't have an octet. Since the hydrogen atoms do not have extra electron pairs with which to make double bonds, there is nothing we can do to solve this problem. 

For obvious reasons, this is called an octet rule violator. In fact, Boron and Beryllium ALWAYS violate the octet rule. Even when it appears that there are enough electrons to fix the octets, as in BF₃,

the boron does not have enough electronegativity to pull electrons away from the fluorine into a bond.

Other Violators