© Copyright Pearson Prentice Hall Radioactivity. © Copyright Pearson Prentice Hall Chemistry Joke Q: What do you get when you put Jim Carrey in jail?

© Copyright Pearson Prentice Hall

Radioactivity


Chemistry Joke

Q: What do you get when you put Jim Carrey in jail?

A: Si


•The presence of too many or too few neutrons relative to protons can cause a nucleus to be unstable.

•An unstable nucleus will change to become stable.

•This process of radioactivity releases a lot of energy

•Also called radioactive decay


•Radioactivity produces both penetrating rays and particles.

•The particles and rays are called radiation.


–Alpha

–Beta

–Gamma

3 Types of Radiation


Alpha Radiation

•Helium nuclei that have been emitted from a radioactive source.

•These emitted particles are called alpha particles.

• Contain two protons and two neutrons—very heavy

•Have a double positive charge. ++

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Nuclear Radiation > Types of Radiation

Equation:


Beta Radiation

An electron resulting from the breaking apart of a neutron in an atom is called a beta particle.

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Nuclear Radiation >

Equation:


Gamma Radiation

•A high-energy photon emitted by a radioisotope is called a gamma ray.

•Often emitted with either alpha or beta particles.

•Has no mass or charge


•Alpha particles are the least penetrating.

•Gamma rays are the most penetrating.

Penetrating Power


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Section Quiz.

1. An unstable nucleus releases energy by

a. emitting radiation.

b. thermal vibrations.

c. a chemical reaction.

d. giving off heat.


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Section Quiz.

2. Which property does NOT describe an alpha particle?

a. 2+ charge

b. a relatively large mass

c. a negative charge

d. low penetrating power


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Section Quiz.

3. When a radioactive nucleus releases a high-speed electron, the process can be described as

a. oxidation.

b. alpha emission.

c. beta emission.

d. gamma radiation.


Slide 15 of 21

Half-Life Section

A half-life (t1/2) is the time required for one-half of a radioisotope sample to decay to products.

After each half-life, half of the existing radioactive atoms have decayed into atoms of a new element.


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Half-Life


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Half-Life


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10.4 h ÷ 2.6 h = 4 half lives

1.0 mg x 0.5 x 0.5 x 0.5 x 0.5 = 0.063 mg

Or…1.0 mg x (0.5)4 = 0.063 mg


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If there were 128 grams of radioactive material initially, what mass remains after four half-lives?

8 grams


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Chemistry Joke

Q: If the formula for water is H20, what’s the formula for ice?

A: H203

© Copyright Pearson Prentice Hall Radioactivity. © Copyright Pearson Prentice Hall Chemistry Joke Q: What do you get when you put Jim Carrey in jail?

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