Which one of the following molecules is a nonpolar molecule? NaCl, CH2Cl2, SO2, BF3
The nonpolar molecule among the options given is BF3 (boron trifluoride).
To determine whether a molecule is nonpolar or not, we need to consider the symmetry of its shape and the electronegativity difference between the atoms involved.
- NaCl (sodium chloride) is an ionic compound and consists of a sodium cation (Na+) and a chloride anion (Cl-). It is not a molecule but a solid crystal lattice and does not possess individual molecules.
- CH2Cl2 (dichloromethane) has a tetrahedral shape with a central carbon atom bonded to two chlorine atoms and two hydrogen atoms. The electron-withdrawing property of the chlorine atoms results in an unequal distribution of electron density, making it a polar molecule.
- SO2 (sulfur dioxide) has a bent shape with a central sulfur atom bonded to two oxygen atoms. The electronegativity difference between sulfur and oxygen creates a polar bond, resulting in a polar molecule.
- BF3 (boron trifluoride) has a trigonal planar shape with a central boron atom bonded to three fluorine atoms. Since all the bonds are evenly distributed around the central atom and the electronegativity difference is negligible, BF3 is a nonpolar molecule.
Therefore, the nonpolar molecule among the options provided is BF3 (boron trifluoride).
To determine whether a molecule is polar or nonpolar, we need to look at the molecular geometry and the presence of polar bonds. Polar bonds occur when there is a difference in electronegativity between atoms, meaning one atom attracts electrons more strongly than the other. If a molecule has polar bonds, it can be polar or nonpolar, depending on the arrangement of the polar bonds in the molecule.
Let's analyze each of the given molecules to determine their polarity:
1. NaCl (sodium chloride): NaCl is an ionic compound composed of a metal (Na) and a nonmetal (Cl). It does not have molecules since it consists of a crystal lattice of alternating positive and negative ions. Since ionic compounds have very strong attractions between positively and negatively charged ions, NaCl is considered nonpolar.
2. CH2Cl2 (dichloromethane): To determine the polarity of CH2Cl2, we need to examine its molecular geometry and the polarity of each bond. CH2Cl2 has a tetrahedral geometry. However, it has two oppositely directed C-Cl bonds, making it asymmetrical. These bonds are polar due to the difference in electronegativity between carbon (C) and chlorine (Cl). Therefore, CH2Cl2 is a polar molecule.
3. SO2 (sulfur dioxide): To determine the polarity of SO2, we again look at its molecular geometry and bond polarities. SO2 has a bent or V-shaped molecular geometry. Sulfur (S) has a higher electronegativity than oxygen (O), resulting in polar S-O bonds. Since the molecule is bent, the polarities of the two S-O bonds do not cancel each other out, making SO2 a polar molecule.
4. BF3 (boron trifluoride): BF3 has a trigonal planar molecular geometry with three F-B-F bonds arranged symmetrically around the central boron (B) atom. All three bonds are polar due to the difference in electronegativity between boron and fluorine. However, since the bond polarities are evenly distributed around the central atom, they cancel each other out, making BF3 a nonpolar molecule.
So, out of the given options, the nonpolar molecule is BF3.