In terms of molecular shape and bond polarity, is sulfur dioxide, SO2, a polar or a nonpolar molecule?

Introduction / Context:
Molecular polarity depends on both the polarity of individual bonds and the overall geometry of the molecule. Sulfur dioxide, SO2, is a common atmospheric gas and a good example of how shape and bond polarity combine to produce a polar molecule. This question asks whether SO2 is polar or nonpolar and requires you to think about electronegativity differences and molecular shape together.

Given Data / Assumptions:

• Molecule: sulfur dioxide, formula SO2.
• Central atom: sulfur, surrounding atoms: two oxygen atoms.
• We consider the usual Lewis structure and VSEPR based geometry.
• Oxygen is more electronegative than sulfur.

Concept / Approach:
A bond is polar when there is a difference in electronegativity between the bonded atoms, causing partial charges. In SO2, sulfur and oxygen differ in electronegativity, so each S O bond is polar. However, to decide if the whole molecule is polar, we must consider the shape. SO2 is not linear; it has a bent or V shaped geometry due to lone pairs on the sulfur atom. In a bent molecule with polar bonds, the bond dipoles do not cancel and produce a net dipole moment, making the molecule polar.

Step-by-Step Solution:
Step 1: Determine whether S O bonds are polar. Oxygen is more electronegative than sulfur, so each S O bond is polar with electron density shifted toward oxygen. Step 2: Draw the Lewis structure of SO2 and count electron domains around sulfur, including lone pairs. Step 3: Apply VSEPR theory; with lone pairs on sulfur and two bonding pairs, the molecular geometry is bent, not linear. Step 4: Represent bond dipoles as arrows from sulfur toward oxygen for each S O bond. Step 5: In a bent arrangement, these dipoles do not cancel; their vector sum is nonzero, leading to a net molecular dipole. Step 6: Conclude that SO2 has polar bonds and an overall polar molecule.

Verification / Alternative check:
You can compare SO2 with CO2. Carbon dioxide is linear with two polar C O bonds that point in exactly opposite directions, causing their dipoles to cancel and giving a nonpolar molecule. In contrast, SO2 has a non linear, bent shape due to lone pairs on sulfur, so the dipoles do not oppose each other directly. Experimental data and reference tables list a nonzero dipole moment for SO2, confirming its polar nature, which matches the prediction from VSEPR theory.

Why Other Options Are Wrong:
Option A claims SO2 has nonpolar bonds and is linear, which is incorrect because S O bonds are polar and the geometry is bent. Option B claims the bonds are polar but the molecule is nonpolar, which would describe a symmetrical arrangement such as CO2, not SO2. Option D claims the bonds are nonpolar but the molecule is polar, which is not consistent, because nonpolar bonds alone cannot create a polar molecule in this context. Only option C correctly describes both the bond polarity and the bent shape leading to a polar molecule.

Common Pitfalls:
Students sometimes memorize that "dioxide" molecules like CO2 are linear and then wrongly assume the same shape for SO2. Another pitfall is to consider only electronegativity differences and forget to check molecular geometry, leading to confusion between polar bonds and polar molecules. Always remember that geometry and symmetry determine whether bond dipoles cancel. For molecules like SO2 with bent shapes and polar bonds, the result is a net molecular dipole and a polar molecule.

Final Answer:
Sulfur dioxide, SO2, has polar S O bonds and, because of its bent shape, is an overall polar molecule.