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(c) doc b(c) doc bDoc Brown's Chemistry KS4 science GCSE/IGCSE/AS Physics Revision Notes

4. Alpha, beta & gamma radiation. 4a. The Properties of the three types of Radioactive Emission and symbols and 4b. The Dangers of Radioactive Emissions - beware of ionising radiations from radio-isotopes!

 Radioisotopes - this page describes the properties of alpha particle radiation, beta particle radiation and gamma radiation in terms of their change, mass, penetration of materials, behaviour in an electric field, the relative ionising capacity and the dangers of ionising radiation from both external radioactive sourcesand internally ingested radionuclide.

Radioactivity & nuclear physics Index 1a. The Structure of Atoms - 3 fundamental particles * 1b. What it is an atom like? * 2a. What is Radioactivity? Why does it happen? * 2b. How did they find out there were three types of atomic-ionising radiation? * 3a. Detection of Radioactivity and its measurement, units * 3b. Ionising Radiation sources * 4a. The properties of the three types of radioactive emission and symbols * 4b The dangers of radioactive emissions - beware of ionising radiation from radio-isotopes! * 5. The uses of radioactive Isotopes emitting alpha, beta or gamma radiation * 6a. The half-life of a radioisotope - how long does material remain radioactive? implications! * 6b. Uses of decay data and half-life values * 7a. What actually happens to the nucleus in alpha and beta radioactive decay? nuclear equations! * 7b. The production of Radioisotopes - artificial sources * 8. Nuclear fusion reactions and the formation of 'heavy elements' * 9. Nuclear Fission Reactions, nuclear power energy resource

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4a. The Properties of the three types of Radioactive Emission and symbols

IONISING RADIATIONS emitted from unstable atomic nuclei

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Type of radiation emitted & symbol

Nature of the radiation

(higher only)

Nuclear Symbol

(higher only)

Penetrating power, and what will block it (more dense material, more radiation is absorbed BUT smaller mass or charge of particle, more penetrating)

Ionising power - the ability to remove electrons from atoms to form positive ions

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Alpha

a helium nucleus of 2 protons and 2 neutrons, mass = 4, charge = +2

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Low penetration, biggest mass and charge, stopped by a few cm of air or thin sheet of paper

Very high ionising power, the biggest mass and charge of the three radiation's, the biggest 'punch'!

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Beta

high kinetic energy electrons, mass = 1/1850, charge = -1

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Moderate penetration, 'middle' values of charge and mass, most stopped by a few mm of metals like aluminium

Moderate ionising power, with a smaller mass and charge than the alpha particle

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Gamma

very high frequency electromagnetic radiation, mass = 0, charge = 0

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Very highly penetrating, smallest mass and charge, most stopped by a thick layer of steel or concrete, but even a few cm of dense lead doesn't stop all of it!

The lowest ionising power of the three, gamma radiation carries no electric charge and has virtually no mass, so not much of a 'punch' when colliding with an atom

uses of alpha, beta and gamma radiation & nuclear equations for alpha and beta decay

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(c) doc b4b. The Dangers of Radioactive Emissions - beware of ionising radiations from radio-isotopes!

The penetration trends and the effects of Ionisation from radioisotopes

All radioactive emissions are extremely dangerous to living organisms. When alpha, beta or gamma radioactive emissions hit living cells they cause ionisation (ionization) effects, they can kill cells directly or cause genetic damage eg to the DNA molecules. High radiation doses cause burn effects and can kill cells. However, low doses don't kill the cells, but if they are genetically damaged and can still replicate, these mutations can lead to the formation of cancerous cells and tumor development later. When alpha, beta and gamma radiation collide with neutral atoms or molecules they knock off electrons and convert them into charged or ionised particles (ions). Positive ions are formed on electron loss and negative ions are formed by electron gain. The positive ions maybe unstable and very reactive and cause other chemical changes in the cell molecules. The 3 radiations have different capacities to cause cell damage.

  • If the radioactive source, a 'radionuclide', gets inside the body the 'danger' order is alpha > beta > gamma.  The bigger the mass or charge of the particle, the bigger its ionising impact on atoms or molecule. BECAUSE the order of mass is 4 > 1/1850 > 0, and for electric charge the order is 2+ > -1 > 0.  If the radioisotope is in the body the radiation impacts directly on cells with the consequences described above.
  • However, if the radioactive source is outside the body, the order danger is reversed to gamma > beta > alpha because the danger order follows the pattern of penetrating power. The smaller the mass and charge the more penetrating the radiation (reverse the order of above). Gamma and beta are the most penetrating and will reach vital organs in the body and be absorbed.  Most gamma passes through soft tissue but some is inevitably absorbed by cells.  Alpha radiation would not penetrate clothing and is highly unlikely to reach living cells.
  • Because of the dangers of this ionising or atomic radiation, all workers and medical staff who are likely to be near radioactive or ionising sources must wear lapel radiation badges containing photographic film to monitor their exposure to radiation. The film is regularly developed and the darker the film the more radiation would have impacted on the person. 
  • Examples of precautions that can be taken include:
    • Radiographers wear lead lined aprons and anyone else involved in radiotherapy cancer treatment must take particular precautions and radiation monitored.
    • In nuclear fuel preparation and reprocessing, as much work is done using robotic control systems in behind steel, concrete, lead or thick lead glass panels for visual monitoring of the situation.
    • In research laboratories, experiments are conducted in sealed fume cupboards at the laboratory side and technicians work through sealed whole arm gloves through a thick lead glass front. You can also reduce the pressure in the fume cupboard so there is no chance of pressure leakage out into the laboratory area.
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(c) doc b(c) doc bRADIOACTIVITY multiple choice QUIZZES and WORKSHEETS

Easier-Foundation Radioactivity Quiz

or Harder-Higher Radioactivity Quiz

 (c) doc b five word-fills on radioactivity * Q2 * Q3 * Q4 * Q5and ANSWERS!

crossword puzzle on radioactivity and ANSWERS!


Revision KS4 Science GCSE/IGCSE/O level Chemistry Information Study Notes for revising for AQA GCSE Science, Edexcel 360Science/IGCSE Chemistry & OCR 21stC Science, OCR Gateway Science  WJEC gcse science chemistry CCEA/CEA gcse science chemistry O Level Chemistry (revise courses equal to US grade 8, grade 9 grade 10) A level Revision notes for GCE Advanced Subsidiary Level AS Advanced Level A2 IB Revise AQA GCE Chemistry OCR GCE Chemistry Edexcel GCE Chemistry Salters Chemistry CIE Chemistry, WJEC GCE AS A2 Chemistry, CCEA/CEA GCE AS A2 Chemistry revising courses for pre-university students (equal to US grade 11 and grade 12 and AP Honours/honors level courses)

Teach yourself chemistry online ALPHABETICAL SITE INDEX for chemistry

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