Which two bonds are most similar in polarity? a) Mg-F and I-Br b) Pb-O and Na-O c) C-F and N-F d) H-F and Cl-F e) K-Cl and Ni-Cl
The Correct Answer and Explanation is:
Correct Answer: (c) C-F and N-F
Explanation:
Polarity in a bond depends on the difference in electronegativity between the two atoms involved. The greater the difference, the more polar the bond. However, when comparing similarity in polarity between two bonds, we look for bonds that have similar electronegativity differences, meaning the two bonds share a comparable degree of electron sharing imbalance.
Let’s analyze each pair:
a) Mg-F and I-Br
Magnesium and fluorine have a large electronegativity difference, resulting in a highly polar (and mostly ionic) bond. Iodine and bromine, on the other hand, are both halogens and have similar electronegativities, creating a nearly nonpolar covalent bond. These two are quite different in polarity.
b) Pb-O and Na-O
Sodium is a highly electropositive metal, forming a strongly ionic bond with oxygen. Lead and oxygen, although also different in electronegativity, form a bond less ionic than Na–O. Their polarities are not similar.
c) C-F and N-F
Carbon has an electronegativity of about 2.5 and fluorine 4.0, giving a difference of 1.5. Nitrogen has an electronegativity of 3.0, resulting in a difference of 1.0 with fluorine. Both C–F and N–F are highly polar covalent bonds, and their electronegativity differences are relatively close. Hence, these two bonds are the most similar in polarity.
d) H-F and Cl-F
Hydrogen and fluorine have a large electronegativity gap, resulting in a very polar bond. Chlorine and fluorine are both halogens and closer in electronegativity, resulting in a less polar bond. These two are not similar.
e) K-Cl and Ni-Cl
Potassium is highly electropositive, forming a very ionic bond with chlorine. Nickel is a transition metal and forms partially covalent bonds with chlorine. Again, these two differ significantly in bond character.
Thus, C-F and N-F are most similar in polarity.
