Radioactivity
To become stable the nuclease gives out radiation
and it is random
*Activity is the rate at which a source of unstable nuclei decay 1Bq=1 decay per second
*Count-rate is the number of decays recorded each second by a detector(Geiger muller tube)
Alpha
- 2 protons 2 neutron same as helium nuclease
- Can be stopped by a single sheet of paper
- Strongly ionising
- High likely to be absorbed and cause damage
Beta
- A high-speed electron
- Ejected from the nuclease as a neutron turns into a proton
- Stopped by a few mm of aluminium
- Quite strongly ionising
- Can penetrate the body to inner organs & can cause damage if absorbed
Gamma
- Type of em radiation
- Emitted from nuclease
- Stopped by several cm of lead
- Weakly ionising
- Likely to pass through living cells without being absorbed
IRRADIATION
IRRADIATION
*Exposing an object to nuclear radiation
*When irradiated it does not emit radiation
*Gloves can be worn to protect against alpha radiation
A lead apron or lead walls and lead glass screen to stop beta and gamma
Radioactive contamination
*Unwanted radioactive isotopes end up on other material this is called contamination
*Hazardous as they decay and emit ionising radiation
*If inhaled by dust or swallowed by food its dangerous it would not be harmful unless entered.(Alpha)
PEER REVIEW-Scientist share what they know with others and check the findings
Half-life
Half life of a radioactive isotope is the time it takes for the number of nuclei of the isotope in a sample to halve
Half life is also the time it take for the count rate from a sample containing the isotope to fall to half its initial level
