Is a polar molecule — Bonding Chemistry Question

STEPS:

1. Define Molecular Polarity: A molecule is considered polar if it has a net dipole moment, which is caused by an asymmetrical distribution of electron density within the molecule.
2. Evaluate Bond Polarity: Determine if the bonds within each molecule are polar. Polar covalent bonds occur between atoms with different electronegativities.
3. Determine Molecular Geometry (VSEPR): Use the number of bonding pairs and lone pairs on the central atom to determine the molecule's three-dimensional shape.
4. Analyze Symmetry: Check if the molecule's shape allows individual bond dipoles to cancel each other out. If a molecule is highly symmetrical (like linear or tetrahedral) and has identical terminal atoms, it is typically nonpolar.
5. Apply to $SO_2$ (Option B): Sulfur has six valence electrons. In $SO_2$, sulfur forms bonds with two oxygen atoms and has one lone pair of electrons remaining on the central atom. According to VSEPR theory, these three electron domains (two bonds and one lone pair) result in a bent molecular geometry. Because this bent shape is asymmetrical, the polar $S-O$ bond dipoles do not cancel, resulting in a net dipole moment.

WHY_OTHERS_WRONG:

• $BeCl_2$ (A): Beryllium forms two single bonds with chlorine and has no lone pairs, resulting in a linear geometry. Because the two polar $Be-Cl$ bonds are equal and point in exactly opposite directions, their dipoles cancel out, making the molecule nonpolar.
• $N_2$ (C), $O_2$ (D), and $F_2$ (E): These are all homonuclear diatomic molecules. Since both atoms in each molecule are identical, there is no difference in electronegativity, the bonds are nonpolar, and the molecules are perfectly symmetrical and nonpolar.