Distinguish between a pure covalent bond and a polar covalent bond.

Distinguish between a pure covalent bond and a polar covalent bond.

• A. Pure covalent: unequal sharing.
• B. Pure covalent: equal sharing of electrons; polar covalent: unequal sharing due to different electronegativities.
• C. Polar covalent: equal sharing.
• D. Pure covalent: ionic bonding.

Answer: (B)

Electronegativity differences control how the shared electron pair is distributed in covalent bonds. In a pure covalent bond, the atoms have very similar electronegativities, so the electrons are shared evenly and the bond is non-polar. In a polar covalent bond, there is a difference in electronegativity, so the shared electrons are pulled more toward the more electronegative atom, creating a partial negative charge on that atom and a partial positive charge on the other. A simple way to see it: H2 has equal sharing (pure covalent), while HCl has unequal sharing due to the H–Cl electronegativity difference (polar covalent). This matches the idea that pure covalent means equal sharing and polar covalent means unequal sharing caused by different electronegativities.

Electronegativity differences control how the shared electron pair is distributed in covalent bonds. In a pure covalent bond, the atoms have very similar electronegativities, so the electrons are shared evenly and the bond is non-polar. In a polar covalent bond, there is a difference in electronegativity, so the shared electrons are pulled more toward the more electronegative atom, creating a partial negative charge on that atom and a partial positive charge on the other. A simple way to see it: H2 has equal sharing (pure covalent), while HCl has unequal sharing due to the H–Cl electronegativity difference (polar covalent). This matches the idea that pure covalent means equal sharing and polar covalent means unequal sharing caused by different electronegativities.