Humber Admissions Practice Test

What defines a polar covalent bond?

1. Atoms have equal electronegativity

2. Electrons are pulled equally between two atoms

3. Atoms differ in electronegativity, resulting in unequal sharing of electrons

4. Electrons are completely transferred

The correct answer is: Atoms differ in electronegativity, resulting in unequal sharing of electrons

A polar covalent bond is characterized by the unequal sharing of electrons between two atoms that have different electronegativity values. Electronegativity refers to an atom's ability to attract and hold electrons. When two atoms form a bond and have significant differences in their electronegativity, the atom with the higher electronegativity will attract the shared electrons more strongly. This unequal attraction causes a partial positive charge on one atom and a partial negative charge on the other, leading to a dipole moment in the molecule. This distinction in electron distribution is what makes the bond polar, as opposed to non-polar covalent bonds where electrons are shared equally due to similar electronegativity values. Additionally, fully transferring electrons between two atoms defines ionic bonds, not polar covalent bonds, which emphasizes the uniqueness of polar covalent interactions.