How can I determine bond polarity?

1 Answer
Jul 20, 2018

Answer:

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
http://www.mikeblaber.org/oldwine/chm1045/notes/Bonding/Polarity/Bond05.htm

Let's take a look at some examples.

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