Rebel Molecules
 Some molecules disobey octet rule
 C, N, O, and F are mostly rule keepers
 1) Odd Number of Valence Electrons
 2) Incomplete Octets
 3) Expanded Valence Shells
 Not every electron is in a pair
 All atoms in the molecule cannot have their octet
satisfied
Ex. NO, NO2
 Molecules with odd valence electron #, not stable
 Very reactive
 Intermediate compounds in a chemical reaction,
short-living
 Not enough electrons to go around !
 Not every atom can achieve the octet rule as a result
 Reactive
 Commonly Be, B, and Al
 GENERALLY,
 A) All Lewis Structures are not necessarily equal for
resonance hybrid
 B) Some resonance structures contribute more to the
structure of the resonance hybrid than others.
**applies only to elements in 3+ periods of periodic
table **
 Valence shell incorporates “d subshell region” (up to 18
electrons)
 More than 8 electrons shared
 Add valence shells if more than 8 valence electrons are
around the central atom
** Applied when not possible to draw Lewis structure
without expanding the shells **
 Complete the Lewis Structure for BrF5
 There is an error in each of these structures. What is
it?
 Only one Lewis Structure is correct. Identify it and
state the problem (s) with the other structures.
 Read pp. 361-366
 Problems pp. 381-382 #53-54, 59-60
 For Thursday, read over lab procedure