1. Bonding
Ionic
Covalent
8.4
Bond Polarity
Polar
Nonpolar

2. nonpolar covalent bond:
The nuclei of atoms pull on the shared electrons, much as the knot in the rope is pulled toward opposing sides in a tug-of-war.

3. + + nonpolar covalent bond:
atoms with equal pull (similar electronegativity) so bonding electrons are shared equally.
H2, N2, O2, F2, Cl2, Br2, I2 + + H H

4. - + polar covalent bond: bonding electrons are shared unequally.
less EN
more EN - + H Cl
 “partial”
dipole: molecule with 2 poles
(partial – end and partial + end)
Which of these bonds is the most polar?
H-Cl H-F O-H C-N
greatest
diff. ΔEN

5. Electronegativity Differences (& Bond Types)
F is a 4.0 (most EN element)
Electronegativity Differences (& Bond Types)
C–H is a NONpolar bond
(2.5 – 2.1 = 0.4)

6. Bonding Summary Ionic Polar Covalent Nonpolar Covalent
(e– transferred)
Polar Covalent
(e– unequally shared)
(ΔEN)
Nonpolar Covalent
(e– equally shared)

7. arranged symmetrically
nonpolar molecule:
has no polar bonds, or…
has polar bonds…
arranged symmetrically Cl Cl
(balanced pull in every direction)
(polar bonds do cancel out)

8. arranged asymmetrically
SHAPE matters
polar molecule:
has polar bonds
arranged asymmetrically
(unbalanced pull in different directions)
(polar bonds do not cancel out)
net dipole

9. Give 2 example of nonpolar molecules: Br2, CO2, CCl4
Quick Quiz!
1. In a nonpolar covalent bond, electrons are
gained by one atom.
shared unequally between atoms.
shared equally between atoms.
lost by both atoms.
Give 2 example of nonpolar molecules:
Br2, CO2, CCl4

10. - + Quick Quiz. 2. In a molecule, the most electronegative atom
repels electrons more strongly and acquires a partial negative charge.
repels electrons more strongly and acquires a partial positive charge.
attracts electrons more strongly and acquires a partial positive charge.
attracts electrons more strongly and acquires a partial negative charge. - +

11. 3. Which of the following bonds is the most polar? H-N O-N H-F Cl-Cl
Quick Quiz.
3. Which of the following bonds is the most polar?
H-N
O-N
H-F
Cl-Cl
greatest difference in EN

12. Quick Quiz.
4. Why is carbon tetrachloride, CCl4,a nonpolar molecule even though it contains 4 polar C–Cl bonds?
The polar bonds are too weak.
The polar bonds cancel in opposite directions.
Carbon is always nonpolar.
Carbon tetrachloride has single bonds.

13. S Quick Quiz. 5. Which of the following is a polar molecule? H2S CO2
NH3 I2 S

14. Cl Cl
AB2
Polar? or
Nonpolar?
AB3
AB4
AB3E
AB4
AB2E2