How can I determine bond polarity?

Jul 20, 2018

Take the difference between the electronegativity value of the 2 atoms in the bond

Explanation:

You'll need to take the difference between the electronegativity value of the two atom. Their bond polarity is determined according to the range it falls in:

• Nonpolar covalent: Electronegativity difference < 0.5
• Polar covalent: Electronegativity difference is 0.5 - 1.6
• Ionic: Electronegativity difference >2

For electronegativity difference 1.7 - 2, it's

• polar covalent if both atoms are nonmetals
• Ionic if one of the atom is a metal

*the ranges may vary slightly depending on which source is used as reference; do check with your school.

Electronegativity values look like this

Let's take a look at some examples.

1. HF - electronegativity difference = 4.0 - 2.1 = 1.9, $\therefore$polar covalent
2. CBr - electronegativity difference = 2.8 - 2.5 = 0.3 $\therefore$nonpolar covalent
3. LiF - electronegativity difference = 4.0 - 1.0 = 3.0 $\therefore$ ionic