Question

Classify the following molecule as a polar and non-polar molecule. Give a reason for your classification.

1. ${\mathrm{H}}_2$
2. ${\mathrm{O}}_2$
3. ${\mathrm{H}}_2\mathrm{O}$
4. ${\mathrm{CCl}}_4$
5. ${\mathrm{NH}}_3$
6. ${\mathrm{Cl}}_2$
7. $\mathrm{HCl}$

Answer 1

Part 1: Polar Molecule:

1. A molecule formed as a result of varying electronegativity between the atoms.
2. There is a partial charge generated on the atoms because of varying electronegativity.

Part 2: Non-polar molecules

1. The charge is evenly distributed in the atoms of the molecule
2. No positive or negative charge is formed.

Part 3: Classification of polar and non-polar molecules

1. ${\mathrm{H}}_2$ - It is a non-polar molecule because it is formed only by the atoms of $\mathrm{H}$ and the electronegativity difference is zero.
2. ${\mathrm{O}}_2$ - It is also a non-polar molecule because it is formed by only the atoms of $\mathrm{O}$ and the electronegativity difference is zero.
3. ${\mathrm{H}}_2\mathrm{O}$ - It is a polar molecule because oxygen and hydrogen have the electronegative difference because along the period electronegativity increases. Electronegativity of $\mathrm{O}$ is $3.44$ and electronegativity of $\mathrm{H}$ is $2.2$
4. ${\mathrm{CCl}}_4$ - It is non-polar because of four identical $\mathrm{C}-\mathrm{Cl}$ bonds present in all directions, which cancels the dipole created because of the varying electronegativity.
5. ${\mathrm{NH}}_3$ - It is a polar molecule because of the uneven distribution of charge between $\mathrm{N}$ and $\mathrm{H}$ atoms, which creates the dipole.
6. ${\mathrm{Cl}}_2$ - It is a non-polar molecule because it is formed only by the atoms of ${\mathrm{Cl}}_2$ and the electronegativity difference is zero
7. $\mathrm{HCl}$ - It is a polar molecule because of the higher electronegativity of $\mathrm{Cl}(3.16)$ than $\mathrm{H}(2.2)$, which creates a dipole in $\mathrm{HCl}$ molecule.