In a polar covalent bond,
A) electrons are shared equally between atoms.
B) electrons are not shared equally between atoms.
C) a cation is bonded to an anion.
The Correct Answer and Explanation is:
The correct answer is B) electrons are not shared equally between atoms.
Explanation:
A polar covalent bond is a type of chemical bond that forms when two atoms share electrons, but the sharing is unequal due to differences in their electronegativity. Electronegativity is a measure of an atom’s ability to attract and hold on to electrons. When two atoms with different electronegativities form a covalent bond, the atom with the higher electronegativity attracts the shared electrons more strongly, resulting in an uneven distribution of electron density.
In a polar covalent bond, one atom will have a partial negative charge (δ-) because it is attracting the electrons more strongly, while the other atom will have a partial positive charge (δ+). This separation of charges creates a dipole, which is characteristic of a polar bond. For example, in a water molecule (H₂O), the oxygen atom is more electronegative than the hydrogen atoms, so the shared electrons spend more time around the oxygen atom, making it slightly negative and leaving the hydrogen atoms slightly positive.
In contrast, a nonpolar covalent bond occurs when two atoms with similar electronegativities share electrons equally or nearly equally. An example of this is the bond between two hydrogen atoms in H₂. In this case, the electrons are shared symmetrically, and there is no significant dipole.
Option A (“electrons are shared equally between atoms”) describes a nonpolar covalent bond, not a polar one. Option C (“a cation is bonded to an anion”) describes an ionic bond, where electrons are not shared but are transferred completely from one atom to another, resulting in oppositely charged ions attracting each other.
Thus, the defining characteristic of a polar covalent bond is the unequal sharing of electrons between atoms.