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Chapter 42: Q. 12 (page 1236)
Calculate the chemical atomic mass of silicon.
The chemical atomic mass of silicon is.
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Use the graph of binding energy to estimate the total energy released if a nucleus with mass number 240 fissions into two nuclei with mass number 120.
What energy (in MeV) alpha particle has a de Broglie wavelength equal to the diameter of nucleus?
The activity of a sample of the cesium isotope 137 Cs, with a half-life of 30 years, is 2.0 * 108 Bq. Many years later, after the sample has fully decayed, how many beta particles will have been emitted?
The plutonium isotope 239 Pu has a half-life of 24,000 years and decays by the emission of a 5.2 MeV alpha particle. Plutonium is not especially dangerous if handled because the activity is low and the alpha radiation doesn’t penetrate the skin. However, there are serious health concerns if even the tiniest particles of plutonium are inhaled and lodge deep in the lungs. This could happen following any kind of fire or explosion that disperses plutonium as dust. Let’s determine the level of danger. a. Soot particles are roughly 1 mm in diameter, and it is known that these particles can go deep into the lungs. How many atoms are in a 1.0@mm@diameter particle of 239 Pu? The density of plutonium is 19,800 kg/m3 . b. What is the activity, in Bq, of a 1.0@mm@diameter particle? c. The activity of the particle is very small, but the penetrating power of alpha particles is also very small. The alpha particles are all stopped, and each deposits its energy in a 50@mm@diameter sphere around the particle. What is the dose, in mSv/year, to this small sphere of tissue in the lungs? Assume that the tissue density is that of water. d. Is this exposure likely to be significant? How does it compare to the natural background of radiation exposure?
Consider a nucleus with mass number . Its mass, within , is atomic mass units.
The fact that cancels means that all nuclei have this density. It is a staggeringly large density, roughly times larger than the density of familiar liquids and solids.
One early objection to Rutherford’s model of a nuclear atom was that matter simply couldn’t have a density this high. Although we have no direct experience with such matter, nuclear matter really is this dense.
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