The dipole moment of a molecule is a measure of the separation of positive and negative charges within a molecule. It is calculated as the product of the magnitude of the charge and the distance between the charges.
In chloromethane, the chlorine atom is more electronegative than the carbon and hydrogen atoms, causing a partial positive charge on the carbon and a partial negative charge on the chlorine. This results in a dipole moment of about 1.6 D.
In fluoromethane, the fluorine atom is even more electronegative than chlorine, creating a larger difference in electronegativity between the carbon and fluorine atoms. This leads to a larger separation of positive and negative charges and a higher dipole moment of about 2.9 D.
Therefore, fluoromethane has a higher dipole moment compared to chloromethane due to the larger electronegativity difference between the carbon and fluorine atoms.
