Nuclear

Notes

Phosphorescence and Henri Becquerel (1896)

• (glow in the dark) - uses the EM spectrum and e^– excitation/emission
• He was testing Uranium to see if phosphorescence was the cause of x-rays.
• He found that Uranium that was not exposed to light of any form produced some form of energy to expose an image onto film.

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The photographic plate from his lab!

More History

• Marie and Pierre Curie– She proposed emission of radioactivity from an atom was due to its unstable atomic nucleus.

She won the Nobel Prize in Physics in 1903 AND the Nobel Prize in Chemistry in 1911!

Marie Curie is the only person ever to win the Nobel Prize in two subjects!

Fission and Fusion

https://youtu.be/3rn339v_Q-w

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Nuclear Fission

• Nuclear fission occurs when a large isotope is bombarded with a neutron.
• This collision causes the larger isotope to break apart into two or more elements.
• These reactions release a lot of energy.

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Fission

Nuclear Fission

• Nuclear power plants produce heat through controlled nuclear fission chain reactions.
• These occur in a nuclear fission reactor.

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Example reaction:

Nuclear Power Plants

• In the U.S., there are approximately 100 nuclear reactors, producing a little more than 20% of the country’s electricity.
• Advantages
• No fossil fuels are burned.
• No combustion products (CO₂, SO₂, etc) to pollute the air and water.
• Disadvantages
• Cost - expensive to build and operate.
• Limited supply of fissionable Uranium-235.
• Accidents (Three Mile Island & Chernobyl)
• Disposal of nuclear wastes

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Nuclear Fusion

• Nuclear fusion is when two or more nuclei combine to form a larger nucleus. (happens mainly on the sun)
• In a fusion reaction, two different hydrogen atoms (deuterium and tritium) combine to form helium, a neutron and lots of energy. There is a HUGE release of energy from this reaction!

H + H 🡪 He + n

2

1

3

1

4

2

1

0

• Fusion would be a superior method of generating power on earth.
• The good news is that the products of the reaction are not radioactive.
• The bad news is that in order to achieve fusion, the material must be in the plasma state at several million kelvins.

Tokamak Fusion Reactor

• heating of a gaseous plasma by means of an electric current and magnetic field
• Tokamak apparatus has been created and shows promise for carrying out these fusion reactions on Earth.

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World’s Largest Tokamak Reactor

• Iter in Southern France
• https://www.iter.org/news/videos

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Pros

Nuclear Fission

• Does not release air pollutants
• Release lots of energy
• Low cost for fuel (Uranium)

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Nuclear Fusion

• Releases more energy than fission
• Does not release air pollutants
• Limitless fuel availability
• Easier to control and stop than fission; no chain reactions.
• No nuclear waste
• Low cost for fuel (deuterium and tritium)

Cons

Nuclear Fission

• can be used by people as a powerful weapon to kill many individuals in an instant.
• It can cause meltdown in the different parts of the globe which is very dangerous to the people who are relying on it as a good source of power.
• Produces lots of radioactive wastes

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Nuclear Fusion

• No full scale production expected until at least 2050
• Commercial power plants would be extremely expensive to build
• Requires extremely high temperatures.

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Radioactive Decay

• Also known as nuclear decay or radioactivity
• It is the process by which the nucleus of an unstable atom loses energy by emitting radiation, including alpha particles, beta particles, gamma rays.

Alpha Decay

• When a radioactive nucleus emits an alpha particle, a new nucleus forms that has
• A mass number 4 less than that of the initial nucleus and an atomic number decreased by 2.
• An alpha particle is a Helium nucleus.
• Example nuclear equation for alpha decay:

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Sg 🡪 Rf + He

263

106

259

104

4

2

Beta Decay

A beta particle

• Is an electron emitted from the nucleus.
• Forms when a neutron in the nucleus breaks down.
• Example nuclear equation for beta decay:

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Gamma Decay

In gamma radiation

• Energy in the form of a wave is emitted from an unstable nucleus, indicated by “m” following the mass number.
• The mass number and the atomic number of the new nucleus are the same.
• Example nuclear equation for gamma decay:

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Alpha (α) particle is two protons and two neutrons; lowest penetrating power.

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Beta (β) particle is a high-energy electron.

0e

-1

Gamma ray is high energy wave released from a nucleus. Highest penetrating power.

γ

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Nuclear Equations

⁶⁰Co 🡪 ⁵⁶Mn + ⁴He

^{27 25 2}

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He + __ 🡪 C + n

All the top numbers and bottom numbers add up to each other! (Law of conservation….)

Also notice the bottom number tells you what the

element is……..

It’s the atomic number

4

2

__

__

12

6

1

0

Called nuclear equations since we use nuclear notation.

Guide to Balancing Nuclear Equations

Steps to balancing a nuclear equation:

1. Write the incomplete nuclear equation(this is normally done for you)

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• Determine the missing mass number

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• Determine the missing atomic number

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• Determine the element symbol for the new mass and atomic number

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• Determine the type of nuclear reaction (alpha, beta, gamma, fusion, fission)