CH110 Hyrbrid Orbitals 1 LRSVDS Chapter 9 part 2: Polarity in Molecules, Valence Bond Theory Read: BLB 9.3–5 HW: BLB 9.33, 35, 38, 43, 47; Packet 9:8-16 Know: polarity of molecules molecular orbitals orbital hybridization Which Skill Check Test Bonus Deadline is Approaching?? __________________________________ When is EXAM 2??? _______________________________ CH110 Hyrbrid Orbitals 2 LRSVDS Polarity in Molecules • Just because a molecule possesses polar bonds does not mean the molecule as a whole will be polar. Dipole Moment (μ) • How can we determine the overall dipole moment for the molecule?
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CH110 Hyrbrid Orbitals 1LRSVDS
Chapter 9 part 2: Polarity in Molecules,
Valence Bond Theory
Read: BLB 9.3–5
HW: BLB 9.33, 35, 38, 43, 47;
Packet 9:8-16
Know:
polarity of molecules
molecular orbitals
orbital hybridization
Which Skill Check Test Bonus Deadlineis Approaching??__________________________________
When is EXAM 2???
_______________________________
CH110 Hyrbrid Orbitals 2LRSVDS
Polarity in Molecules
• Just because a
molecule possesses
polar bonds does not
mean the molecule as
a whole will be polar.
Dipole Moment (µ)
• How can wedetermine theoverall dipolemoment for themolecule?
CH110 Hyrbrid Orbitals 3LRSVDS
Dipole Moment
For a diatomic molecule: µ = Q r
| r | units = debye (D)•!!!• = 3.33 x10"30 C-m
+Q "Q
For two charges (+1 and -1) separated by 1 Å
µ = 4.79 D per Å
Where Q = 1.6 x10"19 C = charge of an electron
For a polyatomic molecule: µ depends on:
1.
2.
CH110 Hyrbrid Orbitals 4LRSVDS
Which molecules are
polar?
CH110 Hyrbrid Orbitals 5LRSVDS
Dipole Trends in H-X
HX bondlength Å
µ(exp)D
µ(ionic)D
!EN % ionic
HF 0.92 1.82 4.41 1.9 41%
HCl 1.27 1.08 6.08 0.9 18%
HBr 1.41 0.82 6.75 0.7 12%
HI 1.61 0.44 7.71 0.4 6%
If the H-X bond were ionic, µ(ionic) = Q r
If the H-Cl bond was ionic (r = 1.27 Å )µ = 4.79 D /Å x 1.27 Å = 6.08 D