10.1 Radioactivity

Understand Radioactivity and distinguish between the types of

decay

• What is nuclear decay?

• What is radiation?

• When unstable nuclei change emitting energy or particles and transforming into an isotope of the same element or a new element.

• The released energy and matter (nuclear radiation is harmful to tissue)

• Light and temperature transfer

4 Types of Nuclear Radiation

• Alpha Particles

• Symbol -α

• Positively charged• Consist of 2 protons and 2

neutrons• Like a Helium nucleus• Most massive of all the types • Does not travel far (barely

into paper) b/c so massive• Remove electrons (ionize)

from matter as they move through.

4 Types of Nuclear Radiation

• Beta particles• Symbol - β

• Negatively charged• A fast moving electron

emitted during decay• Not as massive as alpha• Goes through paper but is

stopped by:– 3 mm Aluminum (Al)– 10 mm Wood

• Also ionizes matter (takes the opposite charge from)

4 Types of Nuclear Radiation

• Gamma rays

• Symbol - γ

• No charge

• Not matter (no mass)

• A form of electromagnetic radiation (like light and x-rays)

• Does not ionize matter

• Very high energy; dangerous!!

• Not easily stopped; only by 60 cm Aluminum or 7 cm lead

4 Types of Nuclear Radiation

• Neutron emission

• Symbol - η

• No charge• Neutrons emitted from

neutron rich nuclei• Matter• Does not ionize other matter

b/c no charge• Travels furthest: needs a

block of lead 15 cm to stop. • Very dangerous!!

• What is background radiation?

• Nuclear radiation that arises naturally from cosmic rays and from radioactive isotopes in the soil and air

• Comes from the sun, soil water and plants

• We get this every day• Won’t hurt us unless gets

to be too much

Dangers and benefits

• What are the dangers of nuclear radiation?

• Can ionize atoms in living tissue• Hemoglobin does not take in oxygen• Other cells no longer function correctly• Skin keeps most rad. Out but some

radiation can be introduced through air, food, and water.

• Burns skin, destroys bone marrow• Accumulated Radon-222 builds up in

basements and destroys lung tissue when inhaled.

• Decrease in white blood cells (cancer)• Changes DNA, causes birth defects

Dangers and Benefits

• What are the beneficial uses of Nuclear radiation?

• Smoke alarms (alpha particles)• Treating cancer w/ small

targeted beams of gamma rays• Use as radioactive tracers:

– Flow of water– Locate tumors– Follow path of drugs– Locate other damaged tissues

• Thickness control• Checking welds• Sterilizing food and equipment

Geiger Counter

• http://www.curtcass.com/detectron/clicks.wav

• The Geiger counter is used to detect nuclear radiation.

• This works because the radiation ionizes the gas inside the tube and creates an electric current.