Which of the following is true of polar covalent bonds

Which of the following is true of polar covalent bonds?

A The electrons are shared unequally.

B The same number of electrons are gained by one atom as are lost by another.

C Electrons are shared equally.

D They are rather weak bonds.

The correct answer and explanation is :

Correct Answer: A) The electrons are shared unequally.

Explanation:

A polar covalent bond is a type of chemical bond where two atoms share electrons unequally due to a difference in their electronegativities—the ability of an atom to attract shared electrons in a bond. This unequal sharing creates a partial positive charge (δ+) on the less electronegative atom and a partial negative charge (δ–) on the more electronegative atom, resulting in a dipole moment.

For example, in a molecule of water (H₂O), oxygen is significantly more electronegative than hydrogen. As a result, the shared electrons spend more time closer to the oxygen atom, making it partially negative and leaving the hydrogen atoms partially positive. This polarity is what gives water many of its unique properties, like its ability to dissolve many substances and its high boiling point.

Now let’s evaluate the other answer choices to see why they are incorrect:

• B) The same number of electrons are gained by one atom as are lost by another.
  This describes ionic bonds, not polar covalent bonds. In ionic bonding, electrons are transferred completely from one atom to another, forming ions.
• C) Electrons are shared equally.
  This defines a nonpolar covalent bond, such as the bond between two hydrogen atoms in an H₂ molecule, where both atoms have the same electronegativity and thus share electrons equally.
• D) They are rather weak bonds.
  Polar covalent bonds are strong chemical bonds, although not as strong as ionic bonds in some cases. They are not considered “weak” in the sense that hydrogen bonds or Van der Waals forces are.

In summary, polar covalent bonds occur when atoms with different electronegativities share electrons unequally, leading to a molecule with partial charges and distinct physical properties.