Why is sulfur dioxide (CS2) considered a nonpolar molecule?
Sulfur dioxide (CS2) is a nonpolar molecule because it's linear molecular geometry and symmetrical arrangement of polar bonds result in a net dipole moment of zero.
Molecular Geometry and Polar Bonds
Molecular geometry: To determine the polarity of a molecule, we need to consider the molecular geometry and the polarity of its individual bonds. In the case of CS2, it consists of a central sulfur atom bonded to two carbon atoms via double bonds. The molecular geometry of CS2 is linear, with the sulfur atom in the center and the carbon atoms on either side.
Polar bonds: Now, let's examine the bond polarities. The S-C bonds in CS2 are polar due to the difference in electronegativity between sulfur (2.58) and carbon (2.55). However, since the molecule is linear and symmetrical, the polarities of the S-C bonds cancel each other out.
Net Dipole Moment
In a nonpolar molecule, the bond polarities should cancel each other due to symmetry, resulting in a net dipole moment of zero. In CS2, the opposing polar bonds along the linear geometry lead to a cancellation of the dipole moments, making the molecule nonpolar.