21 Chemistry -- Chemical Bonding and Shapes of Molecules

Why is benzene molecule non polar whereas chlorobenzene is polar? Give reason.

Why is benzene molecule non polar whereas chlorobenzene is polar? Give reason.

In benzene molecule, carbon and carbon bond can't have polarity because there is not any electronegativity difference and the carbon hydrogen is also not much polar because the electronegativity difference is almost zero and also the small pull due to small difference in Electronegativity is balanced due to even pull from all directions.

In chlorobenzene the electronegativity difference between carbon and chlorine is very high so, it is polar.


(to compare polarity first check electronegativity difference and than the structure of the compound )

Benzene is a nonpolar molecule, while chlorobenzene is a polar molecule. The reason for this difference lies in the chemical structure of these compounds.

Benzene is a cyclic hydrocarbon, consisting of a six-carbon ring with alternating single and double bonds. The electrons in the double bonds are delocalized over the entire ring, creating a uniform electron density around the molecule. This makes the molecule symmetric and nonpolar, with no net dipole moment.

Chlorobenzene, on the other hand, is a derivative of benzene in which one of the hydrogen atoms in the ring has been replaced by a chlorine atom. The chlorine atom is more electronegative than the carbon and hydrogen atoms in the ring, meaning it attracts electrons more strongly. As a result, the electrons in the bond between the carbon and chlorine atoms are pulled towards the chlorine atom, creating a partial negative charge on the chlorine and a partial positive charge on the carbon. This unequal sharing of electrons creates a dipole moment in the molecule, making it polar.

In summary, the difference in polarity between benzene and chlorobenzene is due to the presence of a more electronegative atom in chlorobenzene that creates a dipole moment, whereas benzene has no such electronegative atom and therefore no dipole moment.

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