1. Rāhoroi, 22 Paenga-whāwhā, 2017Rāhoroi, 22 Paenga-whāwhā, 2017
Do now:
Rāhoroi, 22 Paenga-whāwhā, 2017Rāhoroi, 22 Paenga-whāwhā, 2017
Calculate the binding energy of a tritium nucleus, 31H, in Joules and eV
Proton mass = x kg
Neutron mass = x kg
Tritium nucleus = x kg
Electron charge = 1.6 x C
Hint:
Solution:
Ebinding = mdeficitc2
textbook, page 208

2. Today’s Learning Outcomes
1) Define binding energy per nucleon (p209) 2) Sketch and describe the binding energy curves (p209, 210) 3) Describe nuclear fusion and fission in terms of binding energy per nucleon (p210 – 213)

3. Binding Energy per Nucleon
(MeV)
56Fe 8
238U
4He 6
7Li 4 2
Fusion
Fission
Mass number 50
100
150
200

4. Mass per Nucleon

5. Nuclear Fission
Breaking large unstable nuclei into smaller ones

6. Nuclear Fission
When a large nucleus is split into smaller fragments, the fragments have less mass per nucleon
The lost mass is released as energy in the form of kinetic energy of neutrons and gamma rays

7. n
Nuclear Fission U Ba Kr n
Only one neutron is needed to start the reaction, but several are produced U Ba Kr n
This can start a “chain reaction” if there is a “critical mass” of Uranium

8. Nuclear Fission
If the chain reaction is controlled it can be used in a nuclear reactor
- control rods (made of cadmium) absorb neutrons and prevent the chain reaction occurring too rapidly
If it is uncontrolled it explodes as a nuclear or atomic bomb

9. Nucelar Fission and Fusion
Binding energy per nucleon
(MeV)
56Fe 8
238U
4He 6
7Li 4 2
Fusion
Fission
Mass number 50
100
150
200

10. Nuclear Fusion The joining of two small nuclei to form one larger one
For example:
This is the process that powers the sun

11. Nuclear Fusion
Fusing two light atoms together results in a nucleus with less mass per nucleon
The lost mass results in a release of energy

12. Nuclear Fusion
Fusion requires extreme temperature (eg millions of degrees) to occur, and has not practically and economically been used in power generation (yet….)
Hydrogen bombs have been successfully made, but require a fission reaction to provide the necessary temp.

13. Read Chapter 12 – Fission and Fusion
Videos
Read Chapter 12 – Fission and Fusion
Activity 12B
H/W books: Nuclear by Mon 16th