CBSE Class 12-science Answered

Molecules can be grouped as polar or non-polar molecules. Some are also in between.

The arrangement or geometry of the atoms in some molecules is such that one end of the molecule has a positive electrical charge and the other side has a negative charge. If this is the case, the molecule is called a polar molecule, meaning that it has electrical poles. Otherwise, it is called a non-polar molecule.

Examples of polar molecules of materials that are gases under standard conditions are:

• Ammonia (NH₃)
• Sulfur Dioxide (SO₂)
• Hydrogen Sulfide (H₂S).

Also, Ethanol is polar, since its oxygen molecule draws electrons towards it due to its high electro-negativity, causing a negative charge around itself. Water is also an example of polar molecule.

Most hydrocarbon liquids are non-polar molecules.

Examples of non polar molecules include:

• Toluene
• Gasoline

• Hydrogen (H₂)
• Nitrogen (N₂)
• Oxygen (O₂)
• Carbon Dioxide (CO₂)
• Methane (CH₄)
• Ethylene (C₂H₄)