THE NOBLE GASES GROUP 8A

The group 8A elements, known as the noble gases, are all nonmetals that are gases at room temperature. They are all monatomic (that is, they consist of single atoms rather than molecules). Some physical properties of the noble-gas elements are listed in V TABLE 7.8. The high radioactivity of radon (Rn, atomic number 86) has limited the study of its reaction chemistry and some of its properties. 

Electron Boiling Density Element Configuration Point (K) (g/L) Atomic Radius (A) h (kj/mol) 

The element bismuth (Bi, atomic number 83) is the heaviest member of group 5A. A salt of the element, bismuth subsalicylate, is the active ingredient in Pepto-Bismol , an over-the-counter medication for gastric distress. 

Molecular equation Bi203(s) + 6 HN03(n ) Net ionic equation BijOjfs) + 6 H aq) 

In the net ionic equation, nitric acid is a strong acid and Bi(N03)3 is a soluble salt, so we need show only the reaction of the solid with the hydrogen ion forming the Bi ( iq) ion and water. To calculate the concentration of the solution, we proceed as follows (Section 4.5)  

The density of Bi at 25 °C is 9.808 g/ cm. How many Bi atoms are present in a cube of the element that is 5.00 cm on each edge How many moles of the element are present  

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Radon is a member of Group 8A (the noble gases). It is an intermediate product of the radioactive decay of uranium-238. All isotopes of radon are radioactive, but radon-222 is the most hazardous because it has the longest half-life—3.8 days. Radon, which accounts for slightly over half the background radioactivity on Earth, is generated mostly from the phosphate minerals of uranium (Figure 17.27). 

GROUP 8A THE NOBLE GASES Next, we consider the noble gases, the elements of group 8A. which exhibit very limited chemical reactivity. 

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