Radioactivity (6.10-6.16)

• alpha, beta minus, beta positive, gamma rays and neutron radiation are emitted from unstable nuclei in a RANDOM process

so thats ....

• alpha
• beta minus
• beta positive
• gamma rays
• neutron radiation

• alpha, beta minus (electron), beta positive (positron) and gamma rays are all ionising radiation
• alpha, beta and gamma radiation can knock electrons out of atoms causing the atoms to become ions.
• the process is called ionisation
• the radiation causing the ionisation is called ionising radiation

• Radioactive materials occur naturally so everyone is exposed to low-level radation everyday
• this exposure comes from a mixture of manmade and natural sources

• About half is radon gas from the ground
• building and the ground
• cosmic rays
• food and drink
• medical purposes
• nuclear power and weapons testing

• Photographic film is chemically changed ionising radiation so when film is developed any exposure to radiation can be seen
• In Geiger-Muller tubes, the ionising radiation ionises the gas inside, the charged ions move across the chanber and get counted

• Alpha particle is the same as a helium nucleus; it contains two protons and two neutrons
• Beta minus particle is an electron emitted from the nucleus
• A gamma ray is electromagnetic radiation

Penetrating power :

• Alpha - low (stopped by paper and skin)
• Beta - medium (stopped by a sheet of tin foil)
• Gamma - high(intensity reduced by lead/ concrete)

Ionosing power:

• Alpha - high
• Beta - low
• Gamma - very low

Range in air:

• Alpha - 5cm
• Beta - 1m
• Gamma - 1km