Which of the following best explains why the bonds in ammonia (NH3) are polar covalent?
A. Nitrogen has a greater number of isotopes than hydrogen.
B. Nitrogen has a greater electronegativity value than hydrogen.
C. Nitrogen has a mass number that is 14 times that of hydrogen.
D. Nitrogen has seven neutrons, but hydrogen does not have any neutrons.
A?
I don't like any of the choices but B is the best of those listed. Certainly not A.
The correct answer is B. Nitrogen has a greater electronegativity value than hydrogen.
To explain why the bonds in ammonia (NH3) are polar covalent, we need to understand the concept of electronegativity. Electronegativity is a measure of an atom's ability to attract electrons towards itself in a chemical bond.
In a polar covalent bond, there is an unequal sharing of electrons between the atoms involved. One atom tends to pull the shared electrons closer to itself, creating a partial negative charge, while the other atom has a partial positive charge. This creates a separation of charges within the molecule.
In the case of ammonia (NH3), nitrogen (N) and hydrogen (H) are involved in covalent bonding. Nitrogen has a greater electronegativity value (3.04 on the Pauling scale) compared to hydrogen (2.2), meaning that nitrogen has a stronger tendency to attract electrons towards itself.
As a result, in ammonia, the nitrogen atom pulls the shared electrons more towards itself, creating a partial negative charge on the nitrogen atom and partial positive charges on the hydrogen atoms. This unequal sharing of electrons makes the bonds in ammonia polar covalent.
Therefore, option B is the best explanation for why the bonds in ammonia (NH3) are polar covalent.