Chapter 18: The Representative Elements

How is phosphine’s (${\mathbf{\text{PH}}}_{\mathbf{\text{3}}}$) structure different from that of ammonia?

What is the valence electron configuration of Group $\mathbf{\text{6A}}$elements? What are some property differences between oxygen and polonium?

What are the Lewis structures for the two allotropic forms of oxygen? How can the Para magnetism of ${\mathbf{\text{O}}}_{\mathbf{\text{2}}}$be explained using the molecular orbital model? What are the molecular structure and the bond angles in ozone?

Use bond energies to estimate the maximum wavelength of light that will cause the reaction

${\mathbf{\text{O}}}_{\mathbf{\text{3}}}\stackrel{\mathbf{\text{hv}}}{\mathbf{\to }}{\mathbf{\text{O}}}_{\mathbf{\text{2}}}\mathbf{\text{+ O}}$

Ozone is desirable in the upper atmosphere but undesirable in the lower atmosphere. A dictionary states that ozone has the scent of a spring thunderstorm. How can these seemingly conflicting statements be reconciled in terms of the chemical properties of ozone?

Many lithium salts are hygroscopic (absorb water), but the corresponding salts of the other alkali metals are not. Why are lithium salts different from the others?

Ozone is a possible replacement for chlorine in municipal water purification. Unlike chlorine, virtually no ozone remains after treatment. This has good and bad consequences. Explain.

Describe the bonding in ${\mathbf{\text{SO}}}_{\mathbf{\text{2}}}$and ${\mathbf{\text{SO}}}_{\mathbf{\text{3}}}$ using the localized electron model (hybrid orbital theory). How would the molecular orbital model describe the bonding in these two compounds?

The xerographic (dry writing) process was invented in $\mathbf{1938}$by C. Carlson. In xerography, an image is produced on a photoconductor by exposing it to light. Selenium is commonly used, since its conductivity increases three orders of magnitude upon exposure to light in the range from$\mathbf{400}$to$\mathbf{500}\mathbf{}\mathit{n}\mathit{m}$. What color light should be used to cause selenium to become conductive? (See Figure$\mathbf{12}\mathbf{.}\mathbf{3}$)

In large doses, selenium is toxic. However, in moderate intake, selenium is a physiologically important element. How is selenium physiologically important?