Why is carbon tetrachloride non-polar despite having polar bonds?

Carbon tetrachloride is non-polar because its polar bonds are symmetrically arranged, cancelling out the individual bond dipoles.

Carbon tetrachloride (CCl4) is a molecule that consists of a single carbon atom surrounded by four chlorine atoms. The carbon-chlorine bonds are indeed polar, due to the difference in electronegativity between carbon and chlorine. Chlorine is more electronegative than carbon, which means it attracts the shared pair of electrons in the bond more strongly. This results in a partial negative charge on the chlorine atom and a partial positive charge on the carbon atom, creating a dipole across the bond.

However, the overall polarity of a molecule is determined not just by the polarity of its individual bonds, but also by the shape of the molecule. In the case of carbon tetrachloride, the molecule is tetrahedral. This means that the four carbon-chlorine bonds are arranged symmetrically around the carbon atom, with bond angles of 109.5 degrees. This symmetrical arrangement is crucial because it allows the dipoles of the individual bonds to cancel each other out.

Imagine each bond as an arrow pointing from the carbon atom to the chlorine atom, representing the direction of the dipole. In a tetrahedral molecule like carbon tetrachloride, these arrows point in opposite directions and have the same magnitude, so they effectively cancel each other out. This results in a net dipole of zero, meaning that the molecule as a whole is non-polar.

In summary, while the carbon-chlorine bonds in carbon tetrachloride are polar, the molecule itself is non-polar due to its symmetrical tetrahedral shape. This is a good example of how the shape of a molecule can influence its overall polarity, despite the polarity of its individual bonds.