Lecture materials for the Introductory Chemistry course for Forensic Scientists, University of Lincoln, UK. See http://forensicchemistry.lincoln.ac.uk/ for more details.
Asian American Pacific Islander Month DDSD 2024.pptx
Chemical and Physical Properties: Radioactivity & Radioisotopes
1. This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License Radioactivity & Radioisotopes University of Lincoln presentation
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3. This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License Henri Becquerel Marie & Pierre Curie Radioactivity discovered in 1896
4. Stable v. Radioactive Isotopes This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License There are approximately 1,700 isotopes known to exist
5. Chart of the Nuclides This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License
6. This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License Black squares denote STABLE isotopes Z N
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8. Chart of the Nuclides & Radioactivity This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License Z N Neutron RICH Neutron DEFICIENT N/Z = 1–1.6 N/Z > 1.6 N/Z < 1
9. Chart of the Nuclides & Radioactivity This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License Neutron RICH Neutron DEFICIENT E STABLE N/Z <1 Need to gain n + N/Z>1.6 Need to lose n -
10. – Decay (Negatron emission) This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License X X + – A A Z Z+1 n p Parent Daughter Negatron It is easier to convert a neutron to a proton, than expel a neutron from the nucleus
11. Decay This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License E A Z X A m Z+1 X – A Z+1 X – decay (nearly) always results in a daughter in an excited state – if this excited state is fairly long-lived it is called a meta-stable state (m) XS energy is lost by expelling a -ray
12. + Decay (Positron emission) This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License X X + + A A Z Z-1 p n Parent Daughter Positron It is easier to convert a proton to a neutron, than expel a proton from the nucleus
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14. Chart of the Nuclides This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License -emitters
15. Common Radioactive Emissions This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License 0 1.0087 neutron n Neutron 1+ 1.0073 Proton p Proton 1+ 0.00055 positively charged electron + Positron 0 None EMR Gamma 0 None EMR X-ray X-ray 1– 0.00055 electron Beta 2+ 4.0026 He nucleus Alpha Charge Mass Nature Symbol Emission
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17. This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License Half-Life (t ½ ) For example, suppose we had 20,000 atoms of a radioactive substance. If the half-life is 1 hour, how many atoms of that substance would be left after: 12.5% 2,500 3 hours (Three lifetimes) 25% 5,000 2 hours (Two lifetimes) 50% 10,000 1 Hour (one lifetime) % of atoms remaining Number of atoms remaining Time
18. Radioactivity This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License One half life Two half lifes
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24. Cascade effect This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License Radiation Initial disruption 1 st generation of foreign substances that cause further disruption Initial disruption has now been magnified 8 times Continuation in cascade leads to a level of disruption with which the body cannot cope
25. Penetrating Power of Radiation This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License n Skin & paper 5mm brass 6mm Al Pb & concrete Very thick concrete (2m)
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29. Dose Equivalent This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License In theory, 100 Sv -radiation will cause the same biological effect in man as a dose of 100 Sv radiation BUT the absorbed doses are 100 Gy and 5 Gy, respectively
30. Illicit Radioactive Sources Dirty Bombs – Radiation Dispersal Devices (RDD) This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License
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32. Dirty Bombs This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License A SMART PHONE that can detect radiation may soon be helping the police to find the raw materials for radioactive “dirty bombs” before they are deployed. The phones will glean data as the officers carrying them go about their daily business, and the information will be used to draw up maps of radiation that will expose illicit stores of nuclear material. New Scientist (December 2004)
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Notas do Editor
Definition. Soddy – a protégé of Ernest Rutherford and a graduate of Aberystwyth…the Edward Davies Chemistry labs…now closed, he left there to work at Glasgow University where he worked on alpha radiation and established the existence of isotopes…the term was coined over a Dinner in Glasgow where a local GP Dr Margaret Todd suggested the term isotopes from the Greek: iso – same, topos – place. Soddy moved to Aberdeen and then to be Professor of Chemistry at Oxford. He received his Nobel Prize in 1921 for Chemistry.
Hydroxyl free radical also produces hydrogen peroxide – TOXIC to cells – symptoms of radiation sickness are identical to peroxide poisoning
Discuss interaction of radiation with material – the greater the interaction (more ionising power), the shorter the path travelled
![Isotopes ,[object Object],[object Object],This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License Frederick Soddy Nobel Prize (Chemistry) 1921](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)