Which should have the largest dipole moment: \(\mathrm{O}_{3}, \mathrm{H}_{2} \mathrm{O}\), or \(\mathrm{OF}_{2} ?\)

Before calculating the dipole moments, we need to understand the molecular shape of each molecule, as this will affect the distribution of electrons and determine whether there is a net dipole or not. O3 molecule: Ozone (O3) has a bent shape in a resonance structure that shows a double bond between one O-O pair and a single bond between the other O-O pair (O=O-O). H2O molecule: Water (H2O) also has a bent molecular shape. The oxygen atom is at the center and has two hydrogen atoms connected to it. The oxygen atom also has two lone pair electrons (non-bonding electrons). OF2 molecule: Oxygen difluoride (OF2) has a bent molecular shape as well. Oxygen is the central atom and is connected to two fluorine atoms.

Now that we have the molecular shapes, we can determine the electronegativity differences between the atoms which contribute to bond polarities and the overall dipole moment of each molecule. O3 molecule: In O3, there is only one type of bond, O-O, with no electronegativity difference if we do not consider the resonance structure. Hence, there is no net dipole moment in the O3 molecule. H2O molecule: In H2O, we have O-H bonds. Oxygen is more electronegative than Hydrogen (3.44 vs 2.20). Since the molecule is bent, the bond dipoles do not cancel out, resulting in a net dipole moment. OF2 molecule: In OF2, we have O-F bonds. Oxygen is less electronegative than Fluorine (3.44 vs 3.98), but their difference still creates bond dipoles. Similar to H2O, since the molecule is bent, these bond dipoles do not cancel out, leading to a net dipole moment.

After calculating the dipole moments for each molecule, we can now compare them to determine the largest one. O3: No net dipole moment as there is no electronegativity difference. H2O: The bent shape and substantial electronegativity difference between O and H lead to a net dipole moment. OF2: The bent shape and electronegativity difference between O and F also result in a net dipole moment. Comparing the electronegativity differences, \(|3.44-2.20|=1.24\) for H2O, and \(|3.98-3.44|=0.54\) for OF2, it is clear that H2O has a larger dipole moment compared to OF2. Thus, among O3, H2O, and OF2 molecules, H2O has the largest dipole moment.