# Fission and Fusion My Goals for this Lesson

 Date 25.04.2016 Size 48.14 Kb. #17890
Fission and Fusion

My Goals for this Lesson:

• Identify and describe the characteristics and examples of fission and fusion.

• Compare and contrast fission and fusion.

I’m preparing to distinguish between fission and fusion by using their characteristics and examples to compare and contrast them.
Introduction

Use the interactive section to complete this chart.

This formula shows a relationship between and . In regular chemical reactions, mass and energy are both . This means that the measured amounts of mass and energy are the at the beginning and end of a chemical reaction. In a nuclear reaction, scientists have found that mass can be to energy. This is important, especially when you see that a small loss of from an atom’s nucleus releases extremely large amounts of !

The relationship between the mass (m) of an object at rest and the energy (E) of that object can be calculated using Einstein’s formula E = mc2 (where c represents the speed of light).

Elements that have a mass than iron are , often radioactive. These large atoms may undergo one of several types of nuclear reactions.

In a process called nuclear , an atom of uranium may break apart into two smaller atoms. When this happens, the resulting atoms are actually massive in total than the original uranium atoms.

The “missing” mass was converted to according to Einstein’s formula E = mc2, multiplying the lost mass by the speed of light squared determines the amount of given off by each uranium atom as it splits.

It is possible to make the nuclei of two hydrogen atoms together to form one helium nucleus. This requires that the nuclei be hurled at each other at a very high . This process occurs in the , but can possibly be replicated on Earth with the use of lasers, magnets, or in the center of an atomic bomb.

When the two nuclei together, the new nucleus has mass than the two single, separate nuclei. When the nuclei are forced together, this extra mass is released as . The amount of energy released can be predicted using Einstein’s famous formula E = mc2.

Both of these nuclear reactions release a small amount of mass as extremely large amounts of energy.

For example, nuclear fusion is what powers a modern nuclear , and it is also the reaction that produces the energy that is released from the sun.

Nuclear fission, which is powerful than fusion, is what happens in an atomic bomb and in a nuclear power plant.
As you can see, Einstein’s formula was more than just another equation. His discoveries, observations, and , along with the work of other scientists in the field, helped lead to an of the large amounts of power found in the tiny mass of atomic nuclei. These reactions and the large amounts of involved can be very but also potentially . The more we understand about these two types of nuclear reactions, the more informed we will be when making about the uses and applications of this type of in our own communities.

Describe in your own words how each pair of images are related.
 Images Relationship

Lesson

Nuclear Fission

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We know that the particles inside an atom’s nucleus are held together by a . If a large nucleus is split apart, large amounts of can be released. In nuclear fission, certain heavy elements, such as some forms of uranium, are when they are struck by a moving neutron.

When an atom of uranium-235 is struck by a neutron, the atom’s nucleus a neutron and becomes . Instead of giving off an alpha or beta particle, like in the other nuclear reactions that we have studied, the heavy uranium isotope into two or more smaller, medium-weight atoms.
As the nucleus , some free-moving neutrons are released and can with more uranium-235 atoms to cause additional reactions to occur. When the material or substance that starts a reaction, in this case a , is also produced by the reaction and is available to start another reaction, the process is called a chain reaction. This chain reaction will to occur until all of the uranium-235 isotopes have split, or until the neutrons fail to collide with any more uranium-235 nuclei.

The of uranium-235 nuclei produces large amounts of , estimated to be about seven million times that of the explosion of a TNT molecule. This release of energy is what makes nuclear fission useful as an source for communities, but it also comes with possible risks and safety . Most of the energy released by nuclear fission is in the energy of the fission fragments, the smaller atoms produced when the larger atoms splits, and some of the energy is released as radiation.

Nuclear Power Plants

How was nuclear fission introduced to the world?

How much do the following sources contribute to the total electrical power supplied in the United States?

Nuclear power plants

Coal-fired power plants

Gas-fired plants

What percent of electrical power is made with nuclear fission in:

France?

Armenia?

Belgium?

Fill in blanks using the Lesson.

Nuclear power plants, like power plants that use fossil fuels, water to produce steam that turns a large . In a nuclear power plant, a kilogram of uranium, about the size of a , produces more steam, and therefore more electricity, than freight-car loads of coal.

Also, fission reactions do not produce the atmospheric that are associated with the combustion of fossil fuels. However, there are and by-products associated with a nuclear fission that are different than those associated with the use of fossil fuels. By understanding more about nuclear reactions and power plants, we can each make a more decision if someone proposes the construction of a nuclear power plant in our community.
Describe each of the steps in the nuclear power plant process on the lines below:

1

2

3

4

5

6

One of the greatest concerns around the use of nuclear power plants is the of the waste products. The fission reaction used in nuclear power plants generates waste that requires special disposal , and no disposal option that has been used or proposed is considered ideal and without risks or .
Nuclear Fusion

Nuclear fusion is very than nuclear fission, but it still involves large amounts of energy released as the of an atom changes. In nuclear fusion, the nuclei of two very small atoms, such as two hydrogen isotopes, together into one larger nucleus. Do not confuse this with a regular chemical reaction, where atoms combine by sharing electrons. In nuclear fusion, it is the actual that combine together to form one new atom, not the combination or exchange of electrons to form a new compound.

The nuclear-fusion reaction below is one proposed by scientists to someday be used in fusion reactors. In this reaction, two different isotopes of hydrogen, deuterium and tritium, fuse together to form one atom of helium, one neutron, and a very large amount of energy.

Be sure to do the “Let’s Review” section on the Lesson page.