- Highly energetic helium particle - it's of a positive charge and boasts 2 neutrons and 2 protons.
- Can only travel for a few centimetres in air and can be absorbed by a thin sheet of paper and skin - because of its strong positive charge, the radiation ionises other atoms quickly (knocks off electrons). The radiation loses energy quickly, because of this.
- Alpha particles cannot penetrate the skin (least penetrating form of radiation) - if they do enter the body however, the radiation can ionise large numbers of cells within a short distance. (Ionised cells can mutate - cause cancer)
- PRECAUTIONS - This form of radiation can be handled with gloves but must no be inhaled, consumed or placed near eyes/open cuts
- USES - Useful for smoke detectors - Americium releases alpha radiation, which ionises the air within the detector. As smoke from a fire absorbs this form of radiation, the alarm is triggered.
- Electron released from the nucleus of an atom.
- When this type of radiation is produced, one of the neutrons, within the nucleaus, divides into a proton and an electron. The high speed electron, formed here is the the beta particle.
- Particles of a small negative charge - they ionise rather easily and can travel through thin materials. (Eg. Thin metal and paper)
- The particles are much more penetrating than those of alpha radiation - can travel through skin; difficult to prevent this entering the body; less ionising than alpha particles.
- PRECAUTIONS - Those handling beta radiation need to hold the source using tongs, away from the body
- USES - Tracers (doctors use this for medical images; chemicals focus on damaged areas of the body - use of detectors allows images to be created, providing a clear insight into the workings of the body) and monitoring material thickness.
- High frequency (large amounts of energy in a short amount of time)
- Short wavelength
- Difficult to absorb but can penerate most materials (passes through skin, dense metals and concrete)
- PRECAUTIONS - Sources of gamma radiation need to be held with tongs, away from the body and other people; those carrying the substance boast lead lined clothes, to reduce the amount of waves passing through the body.
- USES - Sterilysing food and surgical equipment; treatment of cancer; testing of medical equipment
- "Time taken for the radioactivity to decrease to half of its orignal value,"
- Should a radioactive isotope emit an alpha (2 ps, 2 neuts) or beta (single highly charged electron) particles, the result is a different isotope (as its atomic structure has varied).
- As the decay continues, the number of nuclei, within the isotope of the element, decreases.
- Radioactivity or 'number of counts' is measured in Becquerels (Bq) (Measure the time taken after every 'half' - how long does it take before 80 becomes 40, 20 becomes 10)
The rate of decay depends on numerous factors:
- Type of material/element
- The number of nuceli within the radioactive isotope (greater the amount, greater the rate of decay)
Alpha Decay Formula: (Radon becomes polonium + helium) Beta Decay Formula - Carbon 14 (as a proton and electron are formed from the neutron, the proton number increases)