Answers to Concept Checks

3.1

Symbol Name Describes... Organizational Level Possible  Values

n Principal QN Size Shell 1 to  ∞

l Azimuthal QN Shape Subshell 0 to  n   –   1

ml Magnetic QN Orientation Orbital –    l   to  +l

ms Spin QN Spin —

3.2

Bonding orbitals    are more    stable  than    antibonding orbitals.   Therefore,  antibonding orbitals

have    higher  energy  than    bonding orbitals.

The differences would   be  in  bond    length  (shorter    in  double  bond    than    single),    bond    energy

(higher in  double  bond    than    single),    and molecular   rigidity    (higher in  double  bond    than    single).

Triple  bond    >   double  bond    >   σ   bond    >   π   bond.   Remember    that    while   an  individual  π   bond    is

weaker  than    a   σ   bond,   bond    strength    is  additive.   Therefore,  double  bonds   are stronger    than

single, and triple  bonds   are stronger    still.

3.3
sp orbitals have 50% s character and 50% p character, sp^2 have 33% s character and 67% p
character, and sp^3 have 25% s character and 75% p character.
Resonance structures differ in their placement of electrons in hybridized p-orbitals and require
bond conjugation to delocalize electrons in a molecule. The true electron density is a weighted
average of the resonance structures of a given compound, favoring the most stable structures.