1. E = mc2 NUCLEAR ENERGY FORMULA E = Energy release,J or eV
m = mass defect,kg (*Always in positive number)
c = speed of light = 3 x 108 ms-1

2. E = mc2 NUCLEAR ENERGY m = mass defect
Mass defect = the differences of mass before and after reaction
Atomic mass is too small,therefore it is measured in
Atomic mass unit (a.m.u)
1 a.m.u = 1/12 of mass of carbon-12 atom.
= 1/12 x x kg
= 1.66 x kg

3. NUCLEAR ENERGY 1 a.m.u = 1.66 x 10-27 kg
EXERCISE
Calculate the mass of atoms below in kg
Radium –225 = a.m.u
Radon – 222 = a.m.u
Helium-4 = a.m.u
1 a.m.u = 1.66 x kg
x 1.66 x = x kg
x 1.66 x = x kg
x 1.66 x = x kg

4. Ra Rn He NUCLEAR ENERGY energy + E = mc2 = 8.798 x 10-30 x (3 x 108)2
CALCULATING NUCLEAR ENERGY
Nuclear equation of Radium-226 decay as follows; Ra
226 88 Rn
222 86 + He 4 2
energy
Calculate the total nuclear energy released in Joule and eV.
Given : Ra-226 = a.m.u
Rn-222 = a.m.u
He-4 = a.m.u
Mass before = a.m.u
Mass after =
= a.m.u
E = mc2
Mass defect =
= a.m.u
= x x (3 x 108)2
= x 1.66 x 10-27
= 7.92 x J
= x kg

5. Ra Rn He NUCLEAR ENERGY energy + E = E/e E = 7.92 x 10-13/1.60 x 10-19
CALCULATING NUCLEAR ENERGY
Nuclear equation of Radium-226 decay as follows; Ra
226 88 Rn
222 86 + He 4 2
energy
Calculate the total nuclear energy released in Joule and eV.
Given : Ra-226 = a.m.u
Rn-222 = a.m.u
He-4 = a.m.u
E = E/e
E = 7.92 x 10-13/1.60 x 10-19
E = mc2
= 4.88 x 106 eV
= x x (3 x 108)2
= 7.92 x J

6. U Xe n Sr NUCLEAR ENERGY + energy X 1. Determine the value of X
EXERCISE
Below is a nuclear equation for nuclear reaction; U
235 92 Xe
140 54 n 1 Sr 94 38 +
energy X
Given : U-235 = a.m.u
n = a.m.u
Xe-140 = a.m.u
Sr-94 = a.m.u
1. Determine the value of X
2. Calculate the total nuclear energy released in Joule and eV

7. U Xe n Sr NUCLEAR ENERGY energy + X 1. Determine the value of X
EXERCISE
Below is a nuclear equation for nuclear reaction; U
235 92 Xe
140 54 n 1 Sr 94 38 +
energy X
Given : U-235 = a.m.u
n = a.m.u
Xe-140 = a.m.u
Sr-94 = a.m.u
1. Determine the value of X
Nucleon number
= X
236 = X
X = 2

8. U Xe n Sr NUCLEAR ENERGY energy + 2
EXERCISE
Below is a nuclear equation for nuclear reaction; U
235 92 Xe
140 54 n 1 Sr 94 38 +
energy 2
Given : U-235 = a.m.u
n = a.m.u
Xe-140 = a.m.u
Sr-94 = a.m.u
2. Calculate the total nuclear energy released in Joule and eV.
Mass before =
= a.m.u
Mass after = ( )
= a.m.u

9. U Xe n Sr NUCLEAR ENERGY energy + 2
EXERCISE
Below is a nuclear equation for nuclear reaction; U
235 92 Xe
140 54 n 1 Sr 94 38 +
energy 2
Mass defect = –
= a.m.u
= x 1.66 x 10-27
= x kg
E = mc2
= x x ( 3 x 108)2
= x J
= 1.9 x 108 eV

10. PAST YEARS QUESTION 4 86
a. Complete the equation for the reaction above
b. The nuclear reaction of on nucleus of Radium-226 experience a
mass defect of x kg.Calculate the energy released in
the nuclear reaction.
E = mc2
= x x (3 x 108)2
= 7.76 x J