Classify the C — Cl bond in CCl4 as ionic, polar covalent, or nonpolar covalent. ionic nonpolar covalent polar covalent
The Correct Answer and Explanation is:
Correct Answer: Polar covalent
The carbon–chlorine (C–Cl) bond in carbon tetrachloride (CCl₄) is best classified as polar covalent. This classification is based on the difference in electronegativity between the two atoms involved.
Carbon has an electronegativity of about 2.5, while chlorine has an electronegativity of approximately 3.0. The difference between these values is around 0.5, which falls within the range typically considered to be polar covalent. A bond is generally:
- Nonpolar covalent if the electronegativity difference is less than about 0.4
- Polar covalent if the difference is between roughly 0.4 and 1.7
- Ionic if the difference exceeds 1.7
Because the electronegativity difference in the C–Cl bond is moderate, electrons are shared unequally. Chlorine, being more electronegative, pulls the shared electrons in the bond slightly closer to itself. This creates a partial negative charge (δ–) on the chlorine atom and a partial positive charge (δ+) on the carbon atom, resulting in bond polarity.
However, it is important to note that although each individual C–Cl bond is polar covalent, the molecule CCl₄ itself is nonpolar overall. This is due to its symmetrical tetrahedral shape. The four polar bonds are arranged symmetrically around the central carbon atom, causing their dipole moments to cancel out. As a result, there is no net dipole in the molecule as a whole.
In summary, the C–Cl bond is polar covalent due to the unequal sharing of electrons between carbon and chlorine. The molecule as a whole is nonpolar due to its symmetric geometry, but this does not change the nature of the individual C–Cl bonds.
