Which choice best describes the polarity of BrF5? A) nonpolar bonds / nonpolar molecule B) nonpolar bonds / polar molecule C) polar bonds / polar molecule D) polar bonds / nonpolar molecule
The correct answer and explanation is:
The correct answer is C) polar bonds / polar molecule.
Explanation:
To determine the polarity of BrF5 (bromine pentafluoride), we need to evaluate both the individual bonds and the overall molecular shape.
- Polarity of bonds:
The individual bonds in BrF5 are polar. Bromine (Br) is less electronegative than fluorine (F), so the electron density is drawn more toward the fluorine atoms. This creates a dipole in each Br-F bond, with fluorine being partially negative (δ-) and bromine being partially positive (δ+). - Molecular shape and symmetry:
The molecular shape of BrF5 is square pyramidal. This means that there are five fluorine atoms arranged around a central bromine atom, with one atom above the plane of the fluorine atoms. This shape is not symmetrical because of the lone pairs on the bromine atom. The asymmetry of the molecule prevents the dipoles in the individual bonds from canceling out. In a symmetrical molecule like carbon dioxide (CO2), the dipoles of the bonds cancel each other, resulting in a nonpolar molecule. However, in BrF5, the dipoles do not cancel out due to the square pyramidal shape, leading to an overall polar molecule.
Therefore, the molecule is polar because the individual polar bonds do not cancel each other out. The result is a net dipole moment, making BrF5 a polar molecule with polar bonds.