1. The second-row elements C, N, O,

1. The second-row elements C, N, O, and F should always be assumed to obey the octet rule.2. The second-row elements B and Be often have fewer than eight electrons around them in their compounds. These electron-deficient compounds are very reactive.3. The second-row elements never exceed the octet rule, since their valence orbitals (2s and 2p) can accommodate only eight electrons.4. Third-row and heavier elements often satisfy the octet rule but are assumed in the simplest model to exceed the octet rule by using their empty valence d orbitals.5. When writing the Lewis structure for a molecule, first draw single bonds between all bonded atoms, and then satisfy the octet rule for all the atoms. If electrons remain after the octet rule has been satisfied, place them on the elements having available d orbitals (elements in the third period or beyond).