Refer to the Periodic Table on p. 495 when answering these questions. Q1 Write the equation for the decay of polonium-210 when it undergoes alpha emission. Q2 Write the equation showing the decay of strontium-90 when it emits a beta particle. Q3 Complete the decay chain for radium: 84Po B:214
226 88Ra:A a:218
210 82Pb F: 210
83Bi G:H b: 206
82Pb C:D b:214 82Pb a
84Po E:
Q4 The half-life of carbon-14 is 5 730 years.What fraction of a sample of carbon-14 will remain undecayed after 22 920 years?
Q5 Cobalt-60 is a radioactive isotope with a half-life of 5.26 years and emits beta particles. (i) Write an equation to represent the decay of cobalt-60. (ii) Taking a year as consisting of 365.25 days, calculate the decay constant of cobalt-60. (iii) Calculate the rate of decay of a sample of cobalt-60 when it has 2.5 1021 atoms.
Q6 Radon-222 is an alpha emitter with decay constant of 1.37 1011 s1. (i) Write an equation to represent the decay of radon-222. (ii) Calculate the half-life of radon-222. (iii) If the activity of a sample of radon-222 is 3.014 107 Bq, how many undecayed nuclei are in the sample?
Nuclear Energy Nuclear reactions are those that involve the nuclei of atoms; the orbiting electrons are not involved.There are three types of reactions:
1. Spontaneous emission of , or particles from radioactive nuclei. 2. Nuclear fission, which is the splitting up of a large nucleus into two nuclei of roughly the same size along with a number of individual neutrons.
3. Nuclear fusion, which is the joining of two small nuclei to form a larger nucleus. 408 INVESTIGATING PHYSICS
Bismuth-214
22 years 5 days 140 days
Thorium-230
Thorium-234
Uranium-238
4.5 104 years 24.5 days 1.14 minutes 2.33 104 years 8.3 104 years 1590 years 3.825 days 3.05 minutes 26.8 minutes 19.7 minutes 1.5 104 seconds Half-life
