Which statement best differentiates polar covalent bonds from nonpolar covalent bonds?

Which statement best differentiates polar covalent bonds from nonpolar covalent bonds?

• A. Polar covalent bonds have equal electron attraction; nonpolar have unequal.
• B. Polar covalent bonds have unequal electron attraction; nonpolar have equal.
• C. Polar covalent bonds involve electron transfer; nonpolar involve sharing only.
• D. Polar covalent bonds are always stronger than ionic bonds.

Answer: (B)

Electrons shared in covalent bonds can be shared equally or unequally depending on the atoms’ electronegativities. When the two atoms have similar electronegativities, the shared electrons spend roughly the same time around each nucleus, producing a nonpolar covalent bond with no significant charge separation. When the atoms have different electronegativities, the more electronegative atom pulls the shared electrons closer, creating a polar covalent bond with a partial negative charge on that atom and a partial positive charge on the other. The statement that polar covalent bonds involve unequal electron sharing while nonpolar covalent bonds involve equal sharing captures this distinction. The other options mix in concepts that don’t differentiate these two types: one suggests electron transfer (that would describe ionic bonds, not covalent sharing), and another claims polar covalent bonds are always stronger than ionic bonds (bond strength varies and isn’t the defining difference between polar and nonpolar covalent bonds). Examples help: H–Cl is polar because Cl pulls electron density toward itself; O2 or N2 are nonpolar because the atoms share electrons evenly.

Electrons shared in covalent bonds can be shared equally or unequally depending on the atoms’ electronegativities. When the two atoms have similar electronegativities, the shared electrons spend roughly the same time around each nucleus, producing a nonpolar covalent bond with no significant charge separation. When the atoms have different electronegativities, the more electronegative atom pulls the shared electrons closer, creating a polar covalent bond with a partial negative charge on that atom and a partial positive charge on the other.

The statement that polar covalent bonds involve unequal electron sharing while nonpolar covalent bonds involve equal sharing captures this distinction. The other options mix in concepts that don’t differentiate these two types: one suggests electron transfer (that would describe ionic bonds, not covalent sharing), and another claims polar covalent bonds are always stronger than ionic bonds (bond strength varies and isn’t the defining difference between polar and nonpolar covalent bonds).

Examples help: H–Cl is polar because Cl pulls electron density toward itself; O2 or N2 are nonpolar because the atoms share electrons evenly.