4.3 Electronegativity & Bond Polarity

Polar vs. Non-Polar Covalent Bonds

  • Electrons in a covalent bond (shared pair) may be shared either equally or unequally.

    • Equal(ish)→ Non-Polar
    • 0.5 difference or less
    • Not equal → Polar
    • 0.5 to 1.7

  • Some elements have a stronger ability to attract electrons in a shared pair

  • Example: hydrogen fluoride

    • Contains a single covalent bond
    • Fluorine has the stronger force of attraction so electrons spend more time around it.
    • Contains more protons in nuclear making the radius smaller and pulling electrons in a lot

    Hydrogen Fluoride Molecule

  • Electronegativity: an atom’s ability to attract shared electrons (in a bond) to itself.

  • Fluorine is the most electronegative element with 4.0.

  • We can use EN between elements to determine the nature of a bond.

Dipoles

  • Polar covalent bonds have a permanent separation of charge, we call a dipole.

    Dipoles