Question

Nonpolar molecules often include the

following shapes:
Tetrahedral (CCl4)
Trigonal planar (BF3)
Linear (CS2)
But if the bonds are not ___, then these
shapes will result in polar molecules

Answer 1

Molecules with symmetrical shapes and identical bond moments like CCl4, BF3, and CS2 are nonpolar; however, asymmetry due to different electronegativities or lone pairs leads to polar molecules.

Step-by-step explanation:

The polarity of molecules can be determined by considering both molecular geometry and electronegativity differences. Nonpolar molecules like CCl4 (tetrahedral), BF3 (trigonal planar), and CS2 (linear) have symmetrical shapes with equal bond moments that cancel each other out, leading to a net dipole moment of zero. However, if the bonds in these molecular shapes are not symmetrical, due to atoms with different electronegativities or the presence of lone pairs of electrons on the central atom, the molecules become polar.

For example, replacing a hydrogen atom in CH4 with an atom of different electronegativity makes the molecule polar. Similarly, although BF3 is nonpolar, ammonia (NH3), which is trigonal pyramidal, is polar because its geometry does not allow for cancellation of dipole moments even if the bond moments are identical.