Recall that the octet rule states that an element is surrounded by eight electrons in the Lewis structure.
Exceptions to this rule occur when:
• there is an odd number of electrons, like in radicals
• there are less than 8 electrons or incomplete octet
• there are more than 8 electrons or expanded octet. This occurs to nonmetals from Period 3 to 7.
ClO2- → Cl is the central atom
Total number of valence electrons:
Cl 1 × 7 e– = 7 e–
O 2 × 6 e– = 12 e–
From -1 charge: Add: 1 e–
Total: 20 valence e–
Lewis Structure: (does not obey octet rule)
O's: 8 val e- each, Cl: 10 val e-
Write Lewis structure that obey the octet rule for the following molecules and ions. (In this case the first atom listed is the central atom.
c. ClO2-, SCl2, PCl2-
Considering your answers to parts a, b, and c, what conclusions can you draw concerning the structures of species containing the same number of atoms and the same number of valence electrons?