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Chapter 16 Nuclear Radiation

16.1 Natural Radioactivity

A person working with radioisotopes wears protective clothing and gloves and stands behind a shield.

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Radioactive Isotopes

A radioactive isotope • has an unstable nucleus• emits radiation to become more stable• can be one or more isotopes of an element• is written with a mass number and an atomic

number• includes the mass number in its name

Example: iodine-131

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Examples of Radioactive Isotopes

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Learning Check

Thallium-201 is used for heart scans to determine cardiac function.

A. How many protons are in thallium-201?

B. How many neutrons are in thallium-201?

C. What is the atomic symbol of thallium-201?

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Solution

Thallium-201 is used for heart scans to determine cardiac function.

A. How many protons are in thallium-201? Thallium, symbol Tl, has 81 protons.B. How many neutrons are in thallium-201? mass number 201 atomic number 81 = 120 neutronsC. What is the atomic symbol of thallium-201? mass number 201 Tl atomic number 81

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Nuclear Radiation

Nuclear radiation • is the radiation emitted by an unstable atom• takes the form of alpha particles, neutrons,

beta particles, positrons, or gamma rays

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Alpha Particle

An alpha () particle has• a helium nucleus• 2 protons and 2 neutrons• a mass number of 4• a charge of 2+• a low energy compared to

other radiation particles

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Beta ParticleA beta () particle • is a high-energy electron• has a mass number of 0• has a charge of 1-• forms in an unstable nucleus when a neutron

changes into a proton and an electron

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PositronA positron ( +)• has a mass number of 0• has a charge of 1+• forms in an unstable nucleus when a proton

changes into a neutron and a positron

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Gamma () RayA gamma () ray • is high-energy radiation• has a mass number of 0• has a charge of 0• is emitted from an unstable nucleus to give a

more stable, lower energy nucleus

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Summary of Common Forms of Nuclear Radiation

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Learning Check

Give the mass number and charge of each type of

radiation.

1. alpha particle

2. positron

3. beta particle

4. neutron

5. gamma ray

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Solution

Mass Number Charge

1. alpha particle 4 2+

2. positron 0 1+

3. beta particle 0 1-

4. neutron 1 0

5. gamma ray 0 0

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Radiation protection requires • paper and clothing for alpha particles• a lab coat or gloves for beta particles• a lead shield or a thick concrete wall for gamma

rays• limiting the amount of time spent near a

radioactive source • increasing the distance from the source

Radiation Protection

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Radiation and Shielding Required

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Radiation Protection

Different types of shielding are needed for different radiation particles.

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Learning Check

Indicate the type of radiation (alpha, beta, and/or gamma) protection for each type of shielding.

1) heavy clothing

2) paper

3) lead

4) lab coat

5) thick concrete

A person working with radioisotopes wears protective clothing and gloves and stands behind a shield.

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Solution

Indicate the type of radiation (alpha, beta, and/or

gamma) protection for each type of shielding.

1) heavy clothing alpha, beta

2) paper alpha

3) lead alpha, beta, gamma

4) lab coat alpha, beta

5) thick concrete alpha, beta, gamma