Download SIMPLE NUCLEAR REACTIONS

SIMPLE NUCLEAR REACTIONS
When a reaction causes a change to occur within the nucleus of an atom
it is called a nuclear reaction. When balancing nuclear reactions, the
sum of the mass numbers on both sides must be the same and the sum of
the atomic numbers on both sides must be the same.
NUCLEAR FUSION:
This type of reaction occurs only at extreme temperatures (like the
surface of the sun). Two nuclei combine and a large amount of energy is
released with little waste; scientists are very interested in harnessing this
type of energy.
Ex. deuterium + tritium  helium + neutron + energy
2
1
3
H
+
1
4

H
2
1
He
+
0
n
+ energy
NUCLEAR FISSION:
This type of reaction is used in nuclear power plants around the world.
A neutron is fired at a large nucleus (usually uranium-235). It is
absorbed briefly which makes the unstable isotope of uranium-236. This
then splits into two or more smaller nuclei releasing neutrons and energy
in the process. The products are radioactive.
Ex. uranium-235 + neutron  [uranium-236] (very unstable)
235
92
1
U +
0
236
n 
92
U
[uranium-236]  barium-141 + krypton-92 + 3 neutrons + energy
236
92
141
U 
56
92
Ba
+
36
1
Kr
+ 3
0
n
+ energy
Radioactive Decay
Radioactivity is the result of the disintegration or decay of an unstable
nucleus within an atom. There are three main types of decay:
Alpha Decay ()
An alpha particle contains 2 protons, and 2 neutrons so it is often
referred to as a helium nucleus. Radium-226 is an  emitter.
Ex. 226
222
4
 86 Rn + 2 He
88 Ra
Note: the sum of the atomic mass and the atomic number is the same on
both sides.
Beta Decay ()
A beta particle is the emission of an electron. Carbon-14 will undergo
beta decay as follows:
Ex. 14
14
0

+ -1 e
6 C
7 N
Gamma Decay ()
A gamma ray is a photon with very high energy. Once the photon has
been emitted the nucleus is the same but at a lower energy state.
Gamma rays can be emitted alone or in conjunction with alpha or beta
decay.
Ex.
12
6
12
C* 
6
0
C +
0

Note: The * indicates a high energy state