How do you know or figure out if a chemical bond between several atoms is polar?

1 Answer
Apr 30, 2017

A polar bond is defined when the difference in the electronegativity of 2 atoms is roughly between 0.5 and 2.0


Electronegativity is a property of atoms and describes how strongly an atom attracts the electrons toward the nucleus.

So, for example, an H-F molecule.
The electronegativity for the hydrogen atom is 2.1
The electronegativity of the F atom is 4.1
The difference is therefore 4.1-2.1=2.0
2.0 is roughly a polar bond.

This means that the electrons are pulled towards the F-atom more strongly than towards the Hydrogen atom. This results in the F atom being more negative (attracts the electrons stronger) than the H atom. The electrons are not placed in the middle of the two atoms, but far more to the side of the F-atom.

This gives the F atom a partial negative charge and the H atom a partial positive charge.

  • <0.5 nonpolar bond
  • 0.5-2.0 polar bond
  • 2.0< ionic bond

The borders of these definitions are rough.