Determine whether each molecule given below is polar or nonpolar.
CF4 PBr5 XeF2 SF6
The Correct Answer and Explanation is :
Determining Polarity for CF₄, PBr₅, XeF₂, and SF₆
- CF₄ (Carbon Tetrafluoride)
Molecular Shape: Tetrahedral
Polarity: Nonpolar
CF₄ has a tetrahedral geometry with fluorine atoms symmetrically arranged around the carbon atom. The electronegativity difference between carbon and fluorine creates polar C-F bonds. However, due to the symmetry of the molecule, the dipoles cancel each other out, resulting in a net dipole moment of zero. Thus, CF₄ is nonpolar. - PBr₅ (Phosphorus Pentabromide)
Molecular Shape: Trigonal Bipyramidal
Polarity: Nonpolar
PBr₅ has a trigonal bipyramidal geometry. In this structure, the three bromine atoms in the equatorial plane form a symmetrical triangle, and the two axial bromines are aligned above and below the plane. Because of this symmetry, the dipole moments of individual P-Br bonds cancel out, making the molecule nonpolar overall. - XeF₂ (Xenon Difluoride)
Molecular Shape: Linear
Polarity: Nonpolar
XeF₂ has a linear molecular geometry due to the arrangement of three lone pairs and two bonding pairs of electrons around the xenon atom (VSEPR theory). The two fluorine atoms are positioned directly opposite each other, and their dipole moments cancel out. Therefore, XeF₂ is nonpolar. - SF₆ (Sulfur Hexafluoride)
Molecular Shape: Octahedral
Polarity: Nonpolar
SF₆ has an octahedral geometry, where six fluorine atoms are symmetrically distributed around the central sulfur atom. Each S-F bond is polar, but due to the symmetrical arrangement, the dipole moments cancel out. Consequently, SF₆ is nonpolar.
Summary
While all these molecules have polar bonds, the symmetry of their geometries ensures that the individual bond dipoles cancel each other out, resulting in nonpolar molecules in all four cases.