Chapter 19

The only stable isotope of fluorine is fluorine-19. Predict possible modes of decay for fluorine-21, fluorine-18, and fluorine-17.

In 1994 it was proposed (and eventually accepted) that element 106 be named seaborgium, Sg, in honor of Glenn T. Seaborg, discoverer of the transuranium elements. a. ${}^{263}$ Sg was produced by the bombardment of ${}^{249}\mathrm{Cf}$ with a beam of ${}^{18}\mathrm{O}$ nuclei. Complete and balance an equation for this reaction. b. ${}^{263}$ g decays by $\alpha$ emission. What is the other product resulting from the $\alpha$ decay of ${}^{263}\mathrm{Sg}$ ?

What is the rate of decay from 1.00 mol of radioactive nuclides having the following half-lives: $12,000$ years? 12 hours? 12 seconds?

The rate constant for a certain radioactive nuclide is $1.0\times {10}^{-3}{\mathrm{h}}^{-1}.$ What is the half-life of this nuclide?

Americium-241 is widely used in smoke detectors. The radiation released by this element ionizes particles that are then detected by a charged-particle collector. The half-life of ${}^{24}\mathrm{Am}$ is 433 years, and it decays by emitting $\alpha$ particles. How many $\alpha$ particles are emitted each second by a 5.00 -g sample of ${}^{241}\mathrm{Am}$ ?

The number of radioactive nuclides in a sample decays from $1.00\times {10}^{20}$ to $2.50\times {10}^{19}$ in 10.0 minutes. What is the half-life of this radioactive species?

A chemist wishing to do an experiment requiring ${}^{47}{\mathrm{Ca}}^{2+}$ (half- life $=4.5$ days needs 5.0$\mu \mathrm{g}$ of the nuclide. What mass of ${}^{47}{\mathrm{CaCO}}_3$ must be ordered if it takes 48 $\mathrm{h}$ for delivery from the supplier? Assume that the atomic mass of ${}^{47}\mathrm{Ca}$ is 47.0 $\mathrm{u}.$

Radioactive copper-64 decays with a half-life of 12.8 days. a. What is the value of $k$ in ${\mathrm{s}}^{-1}?$ b. A sample contains 28.0 ${\mathrm{mg}}^{64}\mathrm{Cu}$ . How many decay events will be produced in the first second? Assume the atomic mass of ${}^{64}\mathrm{Cu}$ is 64.0 $\mathrm{u}.$ c. A chemist obtains a fresh sample of ${}^{64}\mathrm{Cu}$ and measures its radioactivity. She then determines that to do an experiment, the radioactivity cannot fall below 25$\mathrm{\%}$ of the initial measured value. How long does she have to do the experiment?

The first atomic explosion was detonated in the desert north of Alamogordo, New Mexico, on July $16,1945.$ What percentage of the strontium- 90$(t_{1/2}=28.9\text{ years) originally produced }$ by that explosion still remains as of July $16,2017?$

Iodine- 131 is used in the diagnosis and treatment of thyroid disease and has a half-life of 8.0 days. If a patient with thyroid disease consumes a sample of ${\mathrm{Na}}^{131}\mathrm{I}$ containing $10.\mu {\mathrm{g}}^{131\mathrm{I}}$ how long will it take for the amount of ${}^{131}\mathrm{I}$ to decrease to 1$/100$ of the original amount?