Which of the following covalent bonds has a polarity with the electron density shifted toward the more electronegative atom, and in which direction does the polarity point?

• A. In the C–H bond, polarity points from H to C.
• B. In the H–Cl bond, polarity points from Cl to H.
• C. In the C–O bond, polarity points from C to H.
• D. In the H–Cl bond, polarity points from H to Cl.

Answer: (D)

Verified step by step guidance

1. Step 1: Understand that bond polarity arises due to differences in electronegativity between two atoms in a covalent bond. The electron density shifts toward the more electronegative atom, creating a dipole moment.
2. Step 2: Identify the electronegativities of the atoms involved in each bond. For example, hydrogen (H) has an electronegativity of about 2.1, carbon (C) about 2.5, oxygen (O) about 3.5, and chlorine (Cl) about 3.0.
3. Step 3: Compare the electronegativities in each bond to determine the direction of electron density shift. The polarity arrow points from the less electronegative atom to the more electronegative atom.
4. Step 4: Analyze each bond: For C–H, since C (2.5) is more electronegative than H (2.1), the polarity points from H to C. For H–Cl, Cl (3.0) is more electronegative than H (2.1), so polarity points from H to Cl. For C–O, O (3.5) is more electronegative than C (2.5), so polarity points from C to O.
5. Step 5: Conclude that the correct statement is that in the H–Cl bond, polarity points from H to Cl, because the electron density shifts toward the more electronegative chlorine atom.