Which choice best describe the polarity of ClF5?
a) The molecule is polar and has polar bonds.
b) The molecule is nonpolar and has polar bonds.
c) The molecule is polar and has nonpolar bonds.
d) The molecule is nonpolar and has nonpolar bonds.
The Correct Answer and Explanation is :
Correct Answer:
a) The molecule is polar and has polar bonds.
Explanation:
Chlorine pentafluoride (ClF₅) is a molecular compound consisting of one chlorine (Cl) atom bonded to five fluorine (F) atoms. To determine its polarity, we must analyze its molecular geometry, electronegativity differences, and dipole moment.
1. Lewis Structure and Molecular Geometry
- Chlorine has 7 valence electrons, and fluorine has 7 valence electrons each.
- When Cl bonds with 5 fluorine atoms, it uses 5 of its valence electrons to form bonds, leaving one lone pair on the chlorine atom.
- The molecular geometry is based on an octahedral electron domain, but since there is one lone pair, the actual molecular shape is square pyramidal.
2. Electronegativity and Bond Polarity
- Fluorine is the most electronegative element (≈3.98), while chlorine is less electronegative (≈3.16).
- This means each Cl–F bond is polar, with the fluorine atoms pulling electron density toward themselves.
- The dipoles do not cancel out completely due to the asymmetry caused by the lone pair.
3. Molecular Polarity
- Because the lone pair distorts the shape, the dipole moments of the Cl–F bonds do not fully cancel each other out.
- This results in an overall dipole moment, making ClF₅ a polar molecule.
Final Conclusion
Since ClF₅ has polar bonds (due to electronegativity differences) and an overall dipole moment (due to asymmetric shape), the best answer is:
(a) The molecule is polar and has polar bonds.