What Is Meant by Polar Molecules and What Are Non-Polar Molecules?

Molecular polarity is a fundamental concept in chemistry that describes how electrons are distributed in a molecule and how this distribution affects the molecule's physical and chemical properties.

Polar Molecules

Polar molecules have an uneven distribution of electrical charges, resulting in a molecule with a positive end and a negative end (a dipole). This occurs when:

• The atoms involved have different electronegativities (the tendency to attract electrons).
• The molecular geometry does not allow the charges to cancel out.

Examples: Water (H₂O), hydrogen fluoride (HF), and ammonia (NH₃) are classic polar molecules. In water, for instance, the oxygen atom is more electronegative than hydrogen, pulling shared electrons closer and creating a partial negative charge on the oxygen and a partial positive charge on the hydrogens.

Non-Polar Molecules

Non-polar molecules have an even distribution of electrical charges, with no distinct poles. This happens when:

• The atoms have similar or identical electronegativities.
• The molecule's geometry is symmetrical, causing any dipole moments to cancel out.

Examples: Nitrogen gas (N₂), oxygen gas (O₂), and methane (CH₄) are non-polar. In these molecules, the electrons are shared equally, and there is no separation of charge.

Difference Between Polar Moecules and Non-Polar 

Why Is This Important?

Polarity affects properties like solubility, melting/boiling points, and reactivity. For example, polar molecules tend to dissolve well in water, while non-polar molecules dissolve in oils or other non-polar solvents.