Transcript Radioactivity

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