Question

Which of the following molecules or ions contain polar bonds: (a) \(\mathrm{P}_{4}\), (b) \(\mathrm{H}_{2} \mathrm{~S}\), (c) \(\mathrm{NO}_{2}^{-}\), (d) \(\mathrm{S}_{2}{ }^{2-}\) ?

Short answer

Among the given molecules or ions, only \(\mathrm{NO}_{2}^{-}\) contains polar bonds. The bonds in \(\mathrm{P}_{4}\), \(\mathrm{H}_{2} \mathrm{~S}\), and \(\mathrm{S}_{2}{ }^{2-}\) are non-polar.

Step-by-step solution

(a) Analyzing \(\mathrm{P}_{4}\) bond polarity

In \(\mathrm{P}_{4}\), there are only phosphorus atoms bonded together. Since all these atoms have the same electronegativity, the bond is non-polar.

(b) Analyzing \(\mathrm{H}_{2} \mathrm{~S}\) bond polarity

For \(\mathrm{H}_{2} \mathrm{~S}\), we have hydrogen atoms bonded to a sulfur atom. The electronegativity values for hydrogen and sulfur are roughly 2.2 and 2.6, respectively. The difference between the electronegativity values is 0.4 which is less than 0.5. Hence, the \(\mathrm{H-S}\) bond is considered non-polar.

(c) Analyzing \(\mathrm{NO}_{2}^{-}\) bond polarity

In the case of \(\mathrm{NO}_{2}^{-}\), we have nitrogen bonded to two oxygen atoms. The electronegativity values for nitrogen and oxygen are 3.0 and 3.5, respectively. The difference between their electronegativity values is 0.5, which falls on the threshold for polarity. Consequently, the \(\mathrm{N-O}\) bond is considered polar.

(d) Analyzing \(\mathrm{S}_{2}{ }^{2-}\) bond polarity

For \(\mathrm{S}_{2} { }^{2-}\), we have two sulfur atoms bonded together. Since both atoms have the same electronegativity, the bond is non-polar. #Summary# In summary, only the \(\mathrm{NO}_{2}^{-}\) molecule contains polar bonds. The other molecules or ions have non-polar bonds.