Octet rule and its exceptions
There are exceptions to the Octet Rule such as Boron and Aluminum atoms needing only six electrons in the structure. Atoms from elements in period three or below might use their available "d" atomic orbitals to accept more than a total of eight valence electrons called an "expanded octet". Sulfur does this quite often and so does Xenon one of only two Noble Gases that chemically combine to form compounds. Exceptions to the Octet Rule:
There are three general ways in which the octet rule breaks down:
1. Molecules with an odd number of electrons
2. Molecules in which an atom has less than an octet
3. Molecules in which an atom has more than an octet
