Lesson 1

What is radon?

Slide 1-2

Which characteristics apply to radon?

• Liquid• Gas• Solid

• Colorless• Grayish-green• Greenish-blue

• Smells like ozone• Has no smell

• Has no taste• Tastes metallic• Tastes like chicken

• Occurs in nature• Made by humans

• Reacts readily chemically• Does not readily react chemically

(is inert)

• Has a static electrical charge• Has no static electrical charge

• Radioactive• Not radioactive

• Harmful to human health• Harmless to human health

See handout 1-1

Slide 1-3

Characteristics of radon

• Liquid• Gas• Solid

• Colorless• Grayish-green• Greenish-blue

• Smells like ozone• Has no smell

• Has no taste• Tastes metallic• Tastes like chicken

• Occurs in nature• Made by humans

• Reacts readily chemically• Does not readily react

chemically (is inert)

• Has a static electrical charge• Has no static electrical

charge

• Radioactive• Not radioactive

• Harmful to human health• Harmless to human health

Slide 1-4

Is there radon in this room?

• Why would we care?– Radon is harmful to human health – Leading cause of lung cancer among

nonsmokers

• How would we know if there were radon in the room?– Radon may occur anywhere– Radon has no color, odor, or taste, so we

cannot detect with our senses– We can tell only by measuring

Slide 1-5

Background for understanding radioactivity

Simple atom• Nucleus

– Protons (+ or positive charge)

– Neutrons (no charge)

• Electrons (- or negative charge)

Slide 1-6

Radon (Rn) atom

Radon is an element: a basic unit of matter

Atomic number = Number of protons86

Atomic mass or mass number =

Number of protons + number of neutrons

Varies

Slide 1-7

Naturally occurring radon isotopes

Isotopes: different forms of an element with different atomic masses

Number of protons

Number of neutrons

Atomic mass

Radon-219 86 133 219

Radon-220 86 134 220

Radon-222 86 136 222

Slide 1-8

Radiation = energy emitted as invisible • Particles• Waves• Rays

Isotopes

• May be stable or unstable• Unstable isotopes

(radioactive) decay spontaneously (change to another element) called– Decay products– Progeny – Daughters

• During decay, unstable isotopes give off radiation

Slide 1-9

Radon decay series

Radon-222

Polonium-218

Bismuth-214

Polonium-214

Lead-210

Lead-214

Slide 1-10

Radon and its decay products

Radon Decay products

Gas Solid

Chemically inactive Chemically active

No static electrical charge

Electrically charged

Primary source of cell damage leading to lung cancer

Slide 1-11

Types of radiation released

Alpha () Beta () Gamma ()

Relatively large mass

Relatively small mass

No mass

= 2 protons and 2 neutrons

= 1 electron = pure energy (electromagnetic radiation)

Electrical charge of +2

Electrical charge of -1

No electrical charge

Moves slowly Moves quickly Moves at the speed of light

Least penetrating Moderately penetrating

Most penetrating

Most damaging to human health

Slide 1-12

Radiation released in radon decay

Radon-222 +

Polonium-218 +

Bismuth-214 +

Polonium-214 +

Lead-210

Lead-214 +

particles damage lung cells

Slide 1-13

Rate of radioactive decay

• Expressed as half-life– Amount of time required for half of atoms to

decay

• Hypothetical example: a box of atoms of an element with half-life of 1 day– After 1 day, 50% of atoms will have decayed– After 2 days, 50% of remaining atoms will have

decayed• Box would contain 25% of original number of atoms

– And so on

Slide 1-14

Hypothetical example1-day half-life in box of atoms

100.00

50.00

25.00

12.506.25 3.13 1.56 0.780

20

40

60

80

100

0 1 2 3 4 5 6 7

Number of days

Percentage of atoms

remaining

Slide 1-15

Half-life of radon3.8 days

In 3.8 days• Radon can move from soil, rock, and water

into air in a home– People breathe in the radon

• As radon decays– It releases radiation– It creates radon decay products, which may

remain in lungs and release more radiation as they decay

• Note: Radon gas is continually entering a home and decaying

Slide 1-16

Half-lives of radon and its decay products

Radon-222 3.8 days

Polonium-218 3.1 minutes

Bismuth-214 19.7 minutes

Polonium-214 160 microseconds

Lead-210 22.6 years

Lead-214 26.8 minutes

Short half-lives

Slide 1-17

Summary

• No color• No smell• No taste• No electrical

charge

• Gas• Radioactive

– Releases damaging particles during decay process

• Naturally occurring• Does not readily react

chemically• Harmful to human health

Radon is an element. What are its characteristics?

See handout 1-2

Slide 1-18

Questions?

Slide 1-19

Check your understanding

• See handout 1-3