CS2, or carbon disulfide, is a nonpolar molecule. To understand why, let’s look at its structure and the concept of polarity.
CS2 has a linear molecular geometry. It consists of one carbon atom double-bonded to two sulfur atoms (S=C=S). The carbon-sulfur bonds are polar because sulfur is more electronegative than carbon, meaning it attracts the shared electrons more strongly.
However, the overall molecule is nonpolar due to its symmetrical shape. The two polar bonds are arranged in such a way that their dipole moments cancel each other out. In other words, the pull of electrons by one sulfur atom is balanced by the equal and opposite pull of the other sulfur atom.
For a molecule to be polar, it must have an uneven distribution of electron density, resulting in a net dipole moment. Since CS2’s dipole moments cancel out, it has no net dipole moment and is therefore nonpolar.
In summary, CS2 is a nonpolar molecule because its linear and symmetrical structure causes the dipole moments of the polar carbon-sulfur bonds to cancel each other out.