Nuclear Reactions:

AN INTRODUCTION

TO FISSION &

FUSION

Nuclear reactions deal with interactions between the nuclei of atoms

The focus of this presentation are the processes of nuclear fission and nuclear fusion

Both fission and fusion processes deal with matter and energy

Introduction

Matter and Energy

In chemical reactions “matter and energy cannot be created nor destroyed”

Nuclear chemistry is differerent

We now need to understand that Matter and Energy are two forms of the same thing

Mass

Matter can be changed into Energy

Einstein’s formula above tells us how the change occurs

In the equation above:

E = Energy

m = Mass

c = Speed of Light (Universal Constant)

EnergyLight

Speed

E = mC2

E = mC2

The equation may be read as follows:

Energy (E) is equal to Mass (m) multiplied by the Speed of Light (c) squared

This tells us that a small amount of mass can be converted into a very large amount of energy because the speed of light (c) is an extremely large number

C= celeretas Latin for swiftness

C = 186,000 miles/second)

Fission

o Fission may be defined as the process of splitting an atomic nucleus into fission fragments

o (Fission splits Big Atoms into little atoms + no)

o The fission fragments are generally in the form of smaller atomic nuclei and neutrons

o Large amounts of energy are produced by the fission process

Fission

Fissile nuclei (nuclei that can split) are generally heavy atoms with large numbers of nucleons (p+ and no)

The nuclei of such heavy atoms are struck by neutrons initiating the fission process

This sticking collision causes spontaneous instability.

Fission occurs due to electrostatic repulsion created by large numbers of protons within the nuclei of heavy atoms

Fission Chain Reaction

U-235 + 1 no U-236 3 no s + Kr-92 + Ba-141 + Energy

(235 +1) = (236) = (3 + 92 + 141 )

1. 1. In this example, a stray neutron strikes an atom of U-235.

2. It absorbs the neutron and becomes an unstable atom of U-236.

3. It then undergoes fission. Notice that more neutrons are released in the reaction.

4. These neutrons can strike other U-235 atoms to initiate their fission and cause a chain reaction if there is enough U-235.

U-235 Fission

Fission

The fission process is an a natural one as a French researcher found a natural uranium reactor in Gabon, West Africa; it has been estimated to be over 2 billion years old

Fission produces large amounts of heat energy and it is this heat that is captured by nuclear power plants to produce electricity

Fusion is a nuclear reaction whereby two light atomic nuclei fuse or combine to form a single larger, heavier nucleus

Which will balance or complete the reaction?

Fusion

Solar Fusion Reaction

Fusion

The fusion process generates tremendous amounts of energy; refer back to Einstein’s equation

For fusion to occur, a large amount of energy is needed to overcome the electrical charges of the nuclei and fuse them together

Fusion

Fusion reactions do not occur naturally on our planet but are the principal type of reaction found in stars

The large masses, densities, and high temperatures of stars provide the initial energies needed to fuel fusion reactions

The sun fuses hydrogen atoms to produce helium, subatomic particles, and vast amounts of energy

Mass and Energy are two forms of the same thing; neither can be created nor destroyed but mass can be converted into energy

(E = mc2)

Fission is a nuclear reaction in which a heavy atomic nucleus is split into lighter atomic nuclei

Fusion is a nuclear reaction in which 2 light atomic nuclei are combined into a single, heavier atomic nucleus

Review

Quiz

1. Which nuclear process produces large amounts of energy?

A. Fission

B. Fusion

C. Both fission & fusion

D. Neither fission nor fusion

Quiz

2. Fission is the process that _________ atomic nuclei.

A. Combines

B. Burns up

C. Stores

D. Splits

Quiz

3. Mass may be converted into energy.

A. True

B. False

Quiz

The fission process requires heavy atomic nuclei.

A. True

B. False

Quiz

4. Name a nuclear reaction that occurs within the sun:

Quiz

5. Fission is a natural process that occurs on the planet Earth.

A. True

B. False

Quiz

6. Explain this equation to your neighbor:

E = mc2

A. What do the parts mean?

B. What is this used for today?

C. Who gave us this equation?