BrCl5 (Bromine Pentachloride) is considered a polar molecule. This might seem surprising at first, but let’s break down the reasoning behind that conclusion.
The molecular geometry of BrCl5 can be described as square pyramidal. This shape arises because the central bromine atom is surrounded by five chlorine atoms, with one chlorine atom positioned above the central plane of the molecule. The symmetrical arrangement of the chlorine atoms around bromine creates unequal distribution of electron density, leading to dipoles.
In terms of electronegativity, chlorine is more electronegative than bromine. As a result, the Br-Cl bonds are polar, with chlorine pulling the electron density towards itself. Because there are five chlorine atoms and only one bromine, the overall dipole moment does not cancel out as it might in more symmetrical molecules. Instead, the dipoles add up, resulting in a molecule that has a net dipole moment.
In conclusion, due to its asymmetrical shape and the polar nature of the bonds between bromine and chlorine, BrCl5 is classified as a polar molecule.