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Physics 12 Assignment
Chapter 19 – Quantum Theory & the Atom
1. Define the following terms:
 continuous spectrum
 line spectrum
 emission spectrum
 absorption spectrum
 Lyman series
 Balmer series
 Paschen series
 quantum number
 Bohr radius
 ground state
 excited states
 binding energy (or ionization energy)
2. In Rutherford’s planetary model of the atom, what keeps the electrons from flying off into space?
3. How can the spectrum of hydrogen contain so many lines when hydrogen contains only one
electron?
4. Use conservation of momentum to explain why photons emitted by hydrogen atoms have slightly
less energy than predicted by the equation Ef – Ei = hf.
5. For the three hydrogen transitions indicated below, with n being the initial state and n’ being the
final state:
 Is the transition an absorption or an emission?
 Which is higher, the initial state energy of the final state energy of the atom?
 Finally, which of these transitions involves the largest energy photon?
(a) n = 1, n’ = 3 (b) n = 6, n’ = 2 (c) n = 4, n’ = 5.
6. What wavelength photon would be required to ionize a hydrogen atom in the ground state and give
the ejected electron a kinetic energy of 10.0 eV?
Physics 12 Assignment
Chapter 20 – The Nucleus & Radioactivity
Chapter 21 – Nuclear Energy
Chapter 20
7. Define the following terms:
•
Proton
•
Neutron
•
Nucleon
•
Chemical symbol
•
Atomic number
•
Atomic mass number
•
Nucleon number
•
Strong nuclear force
•
Nuclide
•
Isotope
•
Mass defect
•
Atomic mass unit
•
•
•
•
•
•
•
•
•
•
•
•
Alpha particle
Beta particle
Gamma ray
Radioactive isotope
Parent nucleus
Daughter nucleus
Transmutation
Ionizing radiation
Neutrino
Antineutrino
Positron
Half-life
8. What do different isotopes of a given element have in common? How are they different?
9. What are the elements represented by the X in the following:
18
82
1
X (e) 247
(a) 232
(d) 38
92 X (b) 7 X (c) 1 X
97 X
10. How many protons and how many neutrons do each of the isotopes in the previous question
have?
11. How do we know there is such a thing as the strong nuclear force?
12. What are the differences between the strong nuclear force and the electric force?
13. What is the experimental evidence in favour of radioactivity being a nuclear process?
14. What element is formed by the radioactive decay of:
24
22
(a) 11
Na (  ) (b) 11
Na (  ) (c) 210
84 Po ( )
15. Fill in the missing particle or nucleus:
(a)
45
20
Ca  ?  e -1  
(d)
234
94
Pu  ?  
(b)
58
29
Cu  ?  
(e)
239
93
Np 239
94 Pu  ?
(c)
46
24
___
Cr  46
23V  ?
16. Can hydrogen or deuterium emit an alpha particle? Explain.
17. Why are many artificially produced radioactive isotopes rare in nature?
18. An isotope has a half-life of one month. After two months, will a given sample of this isotope have
completely decayed? If not, how much remains? Explain.
19. Calculate the binding energy per nucleon for a
14
7
N nucleus. Note: the mass of a
14
7
N nucleus is
14.003074 u.
20. Show that the nucleus 48 Be (mass = 8.005305 u) is unstable to decay into two α particles.
Is 126C stable against decay into three α particles? Show why or why not.
21. How much energy is released when tritium, 13 H , decays by β- emission?
22. A
232
92
U nucleus emits an alpha particle with EK = 5.32 MeV. What is the final nucleus and what is
the approximate atomic mass (in u) of the final atom?
23.What is the energy of the alpha particle emitted in the decay
210
84
Po 206
82 Pb   ?
24. A radioactive material produces 1280 decays per minute at one time, and 6 h later produces 320
decays per minute. What is its half-life?
25. What fraction of a radioactive sample is left after (a) exactly 4 half-lives, (b) exactly 4.5 half-lives?
Chapter 21
26. Define the following terms:
•

•
•
•
•
•
•
•
•
•
Nuclear fission
Nuclear fusion
Critical
Subcritical
Supercritical
Thermal neutron
Moderator
Enriched uranium
Control rods
Primary coolant
Secondary coolant
27. Why are neutrons such good projectiles for producing nuclear reactions?
28. Discuss the relative merits and disadvantages including pollution, and safety, of power generation
by fossil fuels, nuclear fission and nuclear fusion.
29. Light energy emitted by the Sun and stars comes from fusion processes. What conditions in the
interior of stars makes this possible?
30. Calculate the energy released in the fission reaction: (6)
88
1
U  01n 38
Sr 136
54 Xe  12 0 n
235
92
Assume the initial kinetic energy of the neutron is negligible. Use the following table:
Particle
Mass (u)
1
1.008665
0n
235
92
U
235.043923
88
38
Sr
87.90561
136
54
Xe
135.907220
31. Show that the energy released in the fusion reaction below is 17.59 MeV:
2
1
H  13H  24 He  01n