Chapter 21

Why do we sometimes use radioisotopes of toxic elements, such as thallium, for imaging?

Several isotopes of arsenic are used in medical imaging. Which isotope, \(^{72}\) As or \(^{77}\) As, is more likely to be useful for PET imaging?

The World Anti-Doping Agency (WADA) added xenon and argon to the list of banned substances in \(2014 .\) Which intermolecular forces account for the solubility of Xe and Ar in blood?

Helium is used in SCUBA gear to prevent nitrogen narcosis. Do you expect the solubility of He in blood to be greater than or less than the solubility of Xe and Ar in blood?

A patient is injected with a \(5 \mu M\) solution of gallium citrate containing \(^{68} \mathrm{Ga}\left(t_{1 / 2}=9.4 \mathrm{h}\right)\) for a PET study. How long is it before the activity of the \(^{68} \mathrm{Ga}\) drops to \(5 \%\) of its initial value?

Iodine- \(123\left(t_{1 / 2}=13.3 \mathrm{h}\right)\) has replaced iodine- 131 \(\left(t_{1 / 2}=8.1 \mathrm{d}\right)\) for diagnosis of thyroid conditions. How long is it before the activity of \(^{123} \mathrm{I}\) drops to \(5 \%\) of its initial value?

The bismuth in over-the-counter antacids is found as \(\mathrm{BiO}^{+}\) Draw the Lewis structure for the BiO \(^{+}\) cation.

Some medicines used in treating depression contain lithium carbonate. Draw the Lewis structure for \(\mathrm{Li}_{2} \mathrm{CO}_{3}\).

Aluminum hydroxide is used in some antacids. Write a balanced net ionic equation for the reaction of aluminum hydroxide with HCl.

Aluminum carbonate is used in some antacids. Write a balanced net ionic equation for the reaction of aluminum carbonate with hydrochloric acid.

The antacid known as Maalox contains a mixture of magnesium and aluminum hydroxides. Which substance will neutralize more acid on a per-mole basis? Does the same substance also neutralize more acid on a per-gram basis?

Sodium bicarbonate and calcium carbonate both act as antacids and are found in common stomach remedies. Which substance will neutralize more acid on a per- mole basis? Does the same substance also neutralize more acid on a per-gram basis?