Isotope which is unstable.
It emits radiation & changes
into another kind of atom.
Radioactive Isotope
When one kind of nucleus
changes into another kind of
nucleus.
Transmutation Reaction
As stability , energy .
Relationship between
stability and energy
Depends on neutron to
proton ratio.
Stability
All the elements with atomic
number > 83 (or beyond
Bismuth)
Which elements are
unstable?
Alpha, Beta, Gamma
Separated by electric or
magnetic fields.
Types of Radiation
Alpha radiation. Shielding
can be paper or cloth.
Least penetration power
Gamma radiation. Requires
lead/concrete shielding.
Most penetration power
Symbol for alpha
radiation
4
2He
4
or 2
Same as the nucleus of a
helium atom
4
2He
4
or 2
Mass = 4 amu
Charge = +2
4
2He
4
or 2
Symbol for beta particle
0
-1e
or
0
-1
or - or 
Fast moving electron
originating from nucleus
0
-1e
or
0
-1
or - or 
Mass = “zero”
Charge = -1
0
-1e
or
0
-1
or - or 
Symbol for positron.
0
+1e
or
0
+1
or +
Mass = “zero.”
Charge = +1.
Positive electron
0
+1e
or
0
+1
or +
Symbol for gamma
radiation.
0
0
or 
0 mass
0 charge
0
0
or 
Symbol for neutron
1
0n
or n
Symbol for proton
1
1H
or
1
1p
Unstable nucleus emits an
alpha particle. Atomic #
 by 2. Mass #  by 4.
Alpha Decay
Unstable nucleus emits an
alpha particle. Atomic #
 by 2. Mass #  by 4.
220Fr
87
 4 + 216At
2
85
Equation represents natural
transmutation.
1 term on reactant side.
220Fr
87
 4 + 216At
2
85
Balance nuclear equations
using conservation of atomic
number & conservation of
mass number.
220
220Fr
87
87
=
4 + 216
 4 + 216At
2
=
85
2 + 85
Elapsed time
Length of H.L.
# of Half-Lives
Half-Life Map
Mass
Start mass
Elapsed
Time
0
Fraction
Remaining
1
# of Half
Lives
0
1 X H.L.
½
1
2 X H.L.
¼
2
3 X H.L.
1/8
3
4 X H.L.
1/16
4
Same as type of
particle emitted
Decay Mode
Weighted average of the
masses of the naturally
occurring isotopes.
Average Atomic Mass
Particle “bullet” hits target
nucleus & new isotope is produced.
2 terms on reactant side.
Artificial Transmutation
Artificial Transmutation
target
32S
16
bullet
1
+ n
0

32P
15
+
1H
1
Particle “bullet” may be proton or alpha particle.
To react with a nucleus, must overcome + +
repulsive forces by accelerating bullet to high
speeds.
Particle “bullet” may be a neutron. Neutrons have
no charge, so no repulsive forces to overcome. No
acceleration necessary.
Artificial Transmutation
Fission is division.
Large nucleus (U-235 or Pu-239) is split into 2
medium sized nuclei by a neutron bullet. Excess
neutrons & a great deal of energy are also
produced.
Fission
Fission
239Pu
94
147Ba + 3 1n
+ 01n  90
Sr
+
38
56
0
Fusion: U for unite and U for sun.
Very small nuclei (H & He) are jammed together.
Huge amounts of energy are released.
Fusion
Fusion
1H
1
+ 21H  3He
2
a)
b)
1n
0
+
235U
92
59Co
27
c)
3He
2
d)
14C
6
142Ba
56

+ 01n 
60Co
27
+
91Kr
36

14N
7
+ -10e
0
fission
Artificial transmutation
+ 11H  4He + 0e
2
+ 3 1n + energy
+1
fusion
Natural transmutation
Identify each of the rxns