Radioactivity

Radiation

• When you see or hear this word what do you think about? What do you think it means?

• Share your thoughts with me by writing on the post it what you think about when you see this word. Do not put your name on the post it.

Radiation is all around us

• It comes from the Earth and from outer space.

• Many forms of radiation are invisible -- we can't feel it, see it, taste it, or smell it.

• Yet, it can be detected and measured when present.

Everyday we are exposed to Radiation

• Called natural or background radiation.• Natural radiation accounts for about half of our

total annual exposure.• Man-made sources — mostly medical

procedures make up the other 50%.

Natural or Background Radiation

• Radon, a radioactive gas from uranium found in soil dispersed in the air;

• Radioactive Potassium in our food and water; • Uranium, Radium, and Thorium in the Earth's crust;

• And from Cosmic Rays and the Sun.

Man-made radiation sources

• tobacco,

• television,

• medical x-rays,

• smoke detectors,

• lantern mantles,

• nuclear medicine,

• and building materials.

Click Image to calculate your radiation exposure according to the American Nuclear Society.

Watch and Learn

• Everyday Radiation Clip

• Radon Radiation

• Facts About Radiation

• Interactive Sources of Radiation

But what is radiation?

• Radioactive materials are composed of atoms that are unstable.

• An unstable atom gives off its excess energy until it becomes stable.

• The energy emitted is radiation.

Know this…

• While there are several different forms of radiation, we're going to concentrate on just three that result from the decay of radioactive isotopes:

• alpha,

• beta,

• gamma.

Let’s Review What You Already Know

• What are isotopes?

• Element that have the same number of protons, but a different number of neutrons.

• What are radioactive isotopes?

• Isotopes that are radioactive.

Let’s Review

• A radioactive isotope emits particles and energy.

• When the process occurs, the radioactive isotope goes through nuclear decay producing…– An entirely new element or– Another isotope of same element

Nuclear Radiation

• Nuclear radiation = matter and energy released when a radioactive isotope decays

Three types of Radiation

1. Alpha Particles

2. Beta Particles

3. Gamma Rays

Alpha Particles (think charged particle Helium)

• Made of 2 protons and 2 neutrons

• Positively charged (+2)• Emitted from unstable Istotopes • Largest type of nuclear

radiation• Slow speed and low

penetrating distance (1 to 2 inches in air)

• Can be stopped by a sheet of paper or body’s outer layer of skin

• Least harmful type of nuclear radiation

Click Here Americium, in a cloud chamber

Beta Particle (think electron)

• Made up of faster moving and lighter electrons

• Negatively charged• Smaller than alpha

particles• Can travel through 10 ft.

of air pass through a sheet of paper, but can be stopped by aluminum or wood

• While clothing will stop most beta particles, they can penetrate the live layers of skin tissue.

Gamma Rays (think wave or high energy light)

• Not made of matter• No charge• No Mass and Travels at the Speed of Light• Electromagnetic Wave with the most energy• Carry the most energy and the most harmful

radiation. Harmful to internal and external tissue.

• Can only be stopped with thick layer of lead or concrete

Don’t worry…unless your name is Bruce.

Gamma Rays

Nuclear Radiation

Electromagnetic Spectrum

Measuring Radiation

• A Geiger counter has a negatively charged Cu tube with a positively charged wire running through it.

Measuring Radiation

• The tube is filled with gas at low pressure.

• Radiation knocks electrons off the gas which are attracted to the wire producing a current.

Measuring Radiation

• An amplifier strengthens the current producing a clicking sound or a flashing light.

• The number of clicks or flashes per second tell how strong the radiation is.

• Alpha, Beta, and Gamma. Which objects can travel through video. :58 min

• “Whys Guy” shows some everyday radioactive materials. 4:24 min