1. POLARITY OF MOLECULES Molecules can also be described as either polar or nonpolar. nonpolar molecule polar When the individual dipole moments associated with each bond in the molecule cancel out due to symmetry or if no dipole moment exist, the molecule can be classified as a nonpolar molecule. Nonpolar molecules have no overall dipole moment. Otherwise, if an overall dipole moment exist, the molecule is polar.

2. p. 380

6. Fig. 13-10, p. 379

7. Fig. 13-11, p. 380

8. Practice Problems 1. Draw the VSEPR sketch for each of the following showing the polarity of each bond. Describe each molecule as either polar or nonpolar. a) PH 3 b) CH 2 Oc) NO 2 - d) CBr 4 e) C 2 H 6 I) O 2 2. Why would NH 3 have a larger dipole moment than NF 3 ? Trigonal pyramidal, polar Trigonal planar, polar bent, polar Tetrahedral, nonpolarTrigonal planar, nonpolar linear, nonpolar Ammonia has a trigonal pyramidal geometry with the dipoles along each N-H bond pointing inwards to the N-atom & the overall dipole is in one direction up through the lone pair of electrons of N. NF 3 has the dipoles pointing outward to each F-atom and out to the lone pair of electrons thus each dipole counteracts the other reducing the overall effect.

9. Group Study Problems 1. Draw the VSEPR sketch for each of the following showing the polarity of each bond. Describe each molecule as either polar or nonpolar. a) H 2 Sb) H 3 PO 4 c) CF 4 d) CH 2 FCle) C 2 H 2 f) O 3 2. Why would CF 2 H 2 have a larger dipole moment than CCl 2 F 2 ?