Chemistry Regents Practice Test

How is the distribution of charge and the polarity of a CH4 molecule best described?

1. Symmetrical and polar

2. Asymmetrical and polar

3. Symmetrical and nonpolar

4. Asymmetrical and nonpolar

The correct answer is: Symmetrical and nonpolar

The CH4 (methane) molecule consists of one carbon atom centrally located and four hydrogen atoms symmetrically bonded to it in a tetrahedral geometry. This symmetrical arrangement means that the individual bond dipoles that arise due to the difference in electronegativity between carbon and hydrogen effectively cancel each other out. Since carbon and hydrogen have a relatively small difference in electronegativity, the bond dipoles are not strong enough to create a significant overall dipole moment in the molecule. Therefore, the distribution of charge within the CH4 molecule is uniform, leading to a nonpolar classification. The symmetry in its tetrahedral shape ensures that there is no region of the molecule that has a greater concentration of positive or negative charge, which would indicate polarity. Thus, the best description of the charge distribution and polarity of a CH4 molecule is symmetrical and nonpolar.