1. POLARITY AND SOLUBILITY:
“Like dissolves like”

2. 1.a) Review of shapes: What are the five basic shapes?
Linear
Trigonal Planar
Tetrahedral
Trigonal Pyramidal
Bent

3. 1.b) Review of Bonding: Ionic or covalent?
Ionic = metal + nonmetal
Covalent = nonmetal + nonmetal
Nonpolar Covalent = electrons shared equally
Polar Covalent = electrons shared unequally

4. 2. Definitions of Polarity
a)Polar bond—
bond involves unequal distribution of electrons
b)Polar molecule—
the molecule has an unequal distribution of electrons
c)Dipole—charges in a molecule are separated; use and

5. 3. To determine if a molecule is polar you must know its shape!
Draw Lewis Structure & Bar Diagram; Use and to show charge distribution
Determine Shape of Molecule
Determine Polarity of Molecule

6. O—H O H H H a) H2O 1) Lewis & Bar? 2) Shape? 3) Polarity?
Bent-unshared e- pair
Polar—electrons distributed unequally

7. O—F O F F F b) OF2 1) Lewis & Bar? 2) Shape? 3) Polarity?
Bent-unshared e- pair
POLAR—electrons distributed UNequally

8. F—C—F F C F F F b) CF4 1) Lewis & Bar? 2) Shape? 3) Polarity?
tetrahedral
Nonpolar—electrons distributed equally

9. 4. Determining solubility: “Like Dissolves Like”
Polar compounds like water dissolve polar and ionic solids like NaCl
Nonpolar compounds like oils and fats dissolve other nonpolar compounds

10. 5. Like Dissolves Like: Why is this important?
Many pesticides and other dangerous toxins are nonpolar and therefore fat soluble
These nonpolar substances build up in the fat reserves of animals, causing harm
DDT in eagles; PCB’s in humans

11. Determining Solubility Examples: 6. a) Are these pairs soluble?
HCl H2O
Both are polar, therefore they are soluble
O—H H
H—Cl

12. Determining Solubility Examples: 6. b) Are these pairs soluble?
CF4 NH3
CF4 is nonpolar, NH3 is polar; therefore NOT SOLUBLE
F—C—F F
H—N—H H

13. 7.a) Review of shapes: Polarity
Linear-depends
Trigonal Planar-depends
Tetrahedral-depends
Trigonal Pyramidal-ALWAYS polar (unbonded e- pair)
Bent-ALWAYS polar (unbonded e- pair)

14. 7. Practical Application: Chromatography
Pens can be identified using chromatography
Pen ink is a mixture which can be separated using various solvents
A chromatogram (“color picture”) results from the process of chromatography