Polar Bonds and Molecules

Chapter 8.4

Learning Objectives

• Be able to use electronegativity to identify polar vs. non-polar covalent bond

• Draw correct dipoles on a covalent bond

• Draw correct net dipole on a molecular compound

– 1.7 to 4.0: Ionic Bond– 0.3 to 1.7: Polar Covalent Bond– 0.0 to 0.3: Non-Polar Covalent Bond

If the difference in electronegativity is between

Electronegativity Scale

Polar Covalent Bond vs Non-Polar Covalent Bond

Polar Covalent vs Non-Polar Covalent

Drawing Bond Dipoles: BF3

Drawing Bond Dipoles: CH3OH

Net Dipole of Molecules

Dipole – separation of charges within a molecule between two covalently bonded atoms.

Net Dipole – When all the dipole vectors are summed to give one overall dipole.

Let’s PracticeGet out your white boards …

Show the polar bonds (- and +) and then predict the net dipole moment of the molecule. You’ll need to use the electronegativity chart on page 177 of your textbook.

PF3 - phosphorus trifluoride

NH3 - ammonia (nitrogen trihydride)

CCl4 – carbon tetrachloride

BrF5 - bromine pentafluoride