• Opener– Recall: what is Electronegativity? Where can you

find it?– What is the electronegativity of O? What do you

know about the bonds oxygen molecules make in O2(g) ?

– What are the electronegativities of H and Cl?– Based on what you now know about bonding,

what do you anticipate might happen with HCl?

Polar Covalent Bonds

Covalent Bonds

• Remember, Covalent bonds form between two atoms with high ionization energy and high electronegativity

• The two atoms share the electrons between the nuclei

Water

• Water has two polar covalent bonds • The oxygen atom has a higher

electronegativity than the hydrogen, so pulls the shared electron towards itself more than the hydrogen

Polar Covalent Bonds

Since the electron spends more time around the Cl nucleus,the Cl gains a partial negative charge, and the H gains a partial positive chargeThis is indicated in each diagram using the δ

Determining Polarity

• We use electronegativity of each element to determine if a bond is polar

• It is the difference in electronegativity that is important

Check : what is the difference in electronegativity of H-F C-H P-Cl

Bond Continuum

• An ionic bond is just an extreme polar covalent bond where the electron has been transferred from one atom to another

Difference in electronegativty

0 0.4 1.8

Pure Covalent

Polar Covalent Ionic

Determine Polarity

What type of bond forms betweenC and O? Li and Cl?

Li and Se? P and N?

Now try

Draw structural diagrams for each molecule and indicate polarity where appropriate

HBr Cl2

• CH4 CH3OH