© copyright pearson prentice hall radioactivity. © copyright pearson prentice hall chemistry joke...

© 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


Slide 12 of 21

Section Quiz.

1. An unstable nucleus releases energy by

a. emitting radiation.

b. thermal vibrations.

c. a chemical reaction.

d. giving off heat.


Slide 13 of 21

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


Slide 14 of 21

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.


Slide 16 of 21

Half-Life


Slide 17 of 21

Half-Life


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Slide 20 of 21

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


Slide 21 of 21

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

8 grams


Slide 22 of 21

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...

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