Final answer:
To determine if a molecule is polar or nonpolar based on its Lewis structure, you need to draw the Lewis structure, figure out the molecular geometry using VSEPR theory, visualize the geometry, and find the net dipole moment.
Step-by-step explanation:
To determine if a molecule is polar or nonpolar, you should follow these steps:
- Draw the Lewis structure of the molecule.
- Figure out the geometry of the molecule using VSEPR theory.
- Visualize or draw the geometry of the molecule.
- Find the net dipole moment of the molecule. If the net dipole moment is zero, then the molecule is nonpolar. If it is not zero, then the molecule is polar.
For example, if we take the molecule CO₂, the Lewis structure shows that the molecule is linear, with polar C=O bonds on opposite sides of the carbon atom. The bond moments cancel each other out because they are pointed in opposite directions, making CO₂ a nonpolar molecule. On the other hand, the water molecule (H₂O) has a bent molecular structure due to the lone pairs on oxygen, causing the bond moments to not cancel each other out. Therefore, water has a net dipole moment and is a polar molecule.