Lewis Structure for Perchlorate Ion [ENDORSED]

[104822659]

How can Cl have so many valence electrons and form so many double bonds? I thought they have to abide by the octet rule? Do the shells have anything to do with their structure?

[Chem_Mod]

Atoms including P and up can violate the octet rule. Look at p. 84 of the course reader.

[MelanieAu1G]

Cl can have an expanded octet, and therefore form multiple double bonds with the oxygen atoms, because of its location in period 3 which allows for "extra" valence electrons to occupy (or "overflow" into) the 3d orbital. Cl's, and numerous other atoms in period 3 and other succeeding periods, location in this period allows it to break the octet rule. The shells, sub-shells, and orbitals play a role in determining the electron configuration; but, in this case it is not necessary to take them into account in order to deduce the correct Lewis Structure, instead focus on the formal charges for each atom to find the most stable arrangement.