exceptions to octet rule (3.10)

Question 1

why are boron and beryllium exceptions to the octet rule?

Answer 1

Because they tend to form stable compounds/molecules with less than 8 electrons around them – sometimes 8 but not usually.

Question 2

what makes period 3+ exceptions to the octet rule?

Answer 2

they can both satisfy/complete AND exceed the octet rule.

Question 3

why can second-row elements never exceed the octet rule?

Answer 3

the entire second row can only hold up to 8 valence electrons. there is one 2s orbital that can only hold 2 electrons and there are three 2p orbital that can hold up to 6 electrons. in total, that entire row can accommodate 8 electrons.

Question 4

why can third-row elements and beyond exceed the octet rule?

Answer 4

because when we get to the third row and beyond of the periodic table, we gain access to the d orbital. so in this case, the third row consists of the 3s, 3p, AND the 3d orbital. this means they have a larger atomic radius, more space, and available orbitals to accommodate more electrons. although third-row elements don’t normally occupy 3d orbitals, they can sometimes be used during bonding, resulting in the exceeding of the octet rule.