1. POLAR COVALENT BONDS COVALENT= 2 NONMETALS
Polarity and Shape
POLAR COVALENT BONDS
COVALENT= 2 NONMETALS

2. A polar bond in a molecule
may make the entire molecule
polar, with one end slightly
positive and the other end
slightly negative.

3. d + H Cl
d –
Hydrogen chloride is an example
of a polar molecule.

4. In CF4 the fluorines are symmetrically arranged around the carbon.
Tetrahedral Shape

5. The fluorines all pull on the valence
electrons in opposite directions,
effectively cancelling out the polarity
of the bonds

6. There is no partial charge on the molecule.
CF4 has four polar bonds
but it is a non-polar molecule:
There is no partial charge
on the molecule.

7. not symmetrically positioned
The two hydrogens of water are
not symmetrically positioned
around the oxygen.
This is a Bent Shape!

8. d + d – d + The O-H polarities do not cancel,
and the molecule carries a partial charge.

9. Water is a liquid instead of a gas
because the partial positives and negatives
attract each other.

10. This attraction holds the molecules together,
forming a liquid rather than the
spread out molecules of a gas.

12. Molecular Polarity Diatomic molecules: molecular polarity is same as
bond polarity
Molecules with 3 or more atoms:
polarity depends on:
types of bonds and
shape of the molecule

13. Molecular Polarity Depends on 2 factors
1.Type of bonds in the molecule
2. Arrangement of bonds or shape of molecule
Think SYMMETRY!!

14. Polarity of Molecules
A molecule (compound) may contain polar bonds, but not be polar!
Depends on the geometry of the molecule
If molecule is symmetric:
the “pull” of one polar bond is offset by the “pull” of another polar bond
So poles cancel out and molecule/compound is a non polar molecule.

15. Symmetric Molecules
Contain at least one mirror plane

16. Symmetric vs. Asymmetric
CO2 is nonpolar
- electron cloud is symmetric
H2O is polar
- electron cloud is lop-sided (asymmetrical)

17. Polarity of CO2?
Draw an arrow along each bond pointing to the more electronegative atom.
If the arrows cancel out, the molecule is NONPOLAR
THIS IS A LINEAR SHAPE!!

18. Use the structural formula to predict Molecular Polarity
Use the structural formula to predict Molecular Polarity! This is a Tetrahedral Shape!!!! H
H  C  H  

19. Polarity of H2O? The green arrows do not cancel out - water is polar!
This is a bent shape!!!!

20. Ethane = C2H6
Ethene = C2H4
Ethyne = C2H2
These molecules are symmetric and the electron cloud is the same on both ends: they are nonpolar