Week 6 Assignment: (20 points)
1. In your own words, describe what is occurring during the process of
electron beta decay, explaining what is ejected from the unstable
nucleus and focusing subatomic changes. (2 points for clear and
accurate description).
Beta particles are electrons or positrons. Beta decay occurs, in a
nucleus with too many protons or too many neutrons, one of the
protons or neutrons is transformed into the other. Electric charge
conservation requires that if an electrically neutral neutron becomes a
positively charged proton, an electrically negative particle must also
be produced.
2. Write balanced chemical reactions for the following: (1 point each, 4
points total)
a. Cobolt-60 undergoes beta
decay 60/27 Co -> 0/-1 beta
+ 60/28 Ni
b. Americium-241 undergoes alpha
decay 241/95 Am -> 4/2 alpha +
237/93 Np
c. Copper-60 undergoes positron
emission 60/29 Cu -> 0/1 beta +
60/28 Ni
d. Gallium-66 undergoes electron
capture 66/31 Ga -> 0/-1 beta +
66/32 Ge
3. Strontium-89 is an isotope used in the treatment of bone cancer and
has a half- life of 50.57 days. If 20 grams of this isotope is injected
into a patient, how much will remain after 354 days? (1 point for
correct answer with all work shown).
354/50.57 = 7.00019775 then 20grams (0.5^ 7.00019775) = 0.154
grams
4. An isotope has a half-life of 45 minutes. What % of a sample of this
isotope will remain after 1.5 hours, assuming that we start with
100%? (1 point for correct answer with all work shown).
1.5 hours X 60 minutes/ 1 hour = 90 minutes
90 minutes / 45 minutes = 2 half-lives then 100(0.5^2) = 25%
5. Compare and contrast a source of ionizing energy with a source of
