1. NUCLEAR FISSION
A process of splitting of a heavy nucleus into
two lighter nuclei
The heavy nucleus is bombarded by a neutron
At end of the process,it produces ;
Two new nuclei
Three neutrons
Nuclear energy

2. NUCLEAR FISSION
Uranium-235
neutron

3. NUCLEAR FISSION

4. NUCLEAR FISSION
2 new nuclei,3 neutrons and energy produced

5. NUCLEAR FISSION
Barium-141
neutron
neutron
neutron
Uranium-235
neutron
Krypton-92

6. U Kr Ba n NUCLEAR FISSION NUCLEAR FISSION EQUATION + 3 + energy
235 92 Kr 36 Ba
141 56 n 1 + 3
+ energy
EXERCISE
Calculate the nuclear energy produced in the nuclear fission
above in Joule and eV.
Uranium-235 = a.m.u
Krypton-92 = a.m.u
Barium-141 = a.m.u
Neutron = 1.01 a.m.u
2.69 x J

7. U Kr Ba n NUCLEAR FISSION NUCLEAR FISSION EQUATION + 3 + energy
235 92 Kr 36 Ba
141 56 n 1 + 3
+ energy
Mass defect = mass before – mass after
= [ ] – [ (1.01)]
= 0.18 a.m.u
= 0.18 x 1.66 x kg
= x kg
E = mc2
= x x (3.0 x 108)2
= 2.69 x J
= 1.68 x 108 eV

8. NUCLEAR FISSION CHAIN REACTION
A chain reaction occurs when a further nuclear fission is
continuously occurred.
This is happen when the neutron which is produced in earlier
nuclear fission bombarding the new nuclei.
Again,the process will produce 2 new nuclei,3 neutron and nuclear
energy.
Chain reaction only can happen when the mass of uranium is
exceeded the critical mass.

9. NUCLEAR FISSION
CHAIN REACTION
neutron

10. NUCLEAR FISSION
CHAIN REACTION
neutron

11. PAST YEARS QUESTION A. 3.22 x 10-28 kg B. 9.67 x 10-20 kg C.
In the fission reaction for an atom of uranium-235,the energy
produced is 2.9 x J.What is the total loss of mass in the
reaction ? A.
3.22 x kg
E = mc2
2.9 x = m x (3 x 108)2 B.
9.67 x kg
m = 3.22 x kg C.
2.61 x 106 kg D.
1.03 x 1019 kg

12. PAST YEARS QUESTION a. What is meant by nuclear fission ?
A process of splitting a heavy nucleus into two lighter nuclei
b. What is meant by nuclear fusion ?
A process of combining two heavy nuclei to form a heavier nucleus

13. PAST YEARS QUESTION
c. Using the information in the table,compare the nuclear fission and
nuclear fusion.Hence state the relationship between mass and
energy evolved.
1. Nuclear fission is a process of splitting a heavy nucleus to
lighter nuclei while nuclear fusion is a process of combining
light nuclei to heavier nucleus
2. Both reactions release nuclear energy
3. Nuclear energy released due to mass loss

14. PAST YEARS QUESTION
Describe how the chain reaction happens in a nuclear fission of an atom of uranium.
neutron
Heavy nucleus
3 neutrons
Heavy nucleus is bombarded
by neutron
Heavy nucleus
Two lighter nuclei and three
neutron are produced
Light nucleus
Neutron continue to hit the
new nuclei and produce two
lighter nuclei and three neutron