Covalent bonds can be either polar or nonpolar. This depends on how strongly the two atoms in the bond attract electrons. We use a term called electronegativity to explain this attraction. Electronegativity tells us how good an atom is at pulling electrons toward itself.

Electronegativity and Bond Type:

• Nonpolar Covalent Bonds:

  • When the difference in electronegativity between two atoms is between 0.0 and 0.4, the bond is nonpolar.
  • For example, in molecules like H₂ (hydrogen) or Cl₂ (chlorine), both atoms have the same electronegativity. This means they share their electrons equally.

• Polar Covalent Bonds:

  • When the difference in electronegativity is between 0.5 and 1.7, the bond is polar.
  • A great example of this is water (H₂O). Oxygen has an electronegativity of 3.5, while hydrogen has 2.1. This gives us a difference of 1.4, which leads to an unequal sharing of electrons.

Key Characteristics:

• In polar bonds, one end of the molecule becomes slightly negative (known as δ-) and the other end becomes slightly positive (δ+). This creates a dipole moment.
• In nonpolar bonds, the electrons are shared equally, so there is no dipole moment.

Understanding whether a bond is polar or nonpolar is important. It helps us predict how molecules will act and interact with each other in chemical reactions.