Effects Of Alpha, Beta & Gamma Radiation On The Atom

1. Effects Of Alpha, Beta & Gamma Radiation On The Atom Noadswood Science, 2012

2. Effects Of Alpha, Beta & Gamma Radiation On The Atom • To understand the effect of alpha, beta and gamma radiation on the atom

3. Radioactivity Anagrams • See if you can solve the anagrams: - • Daratiion • Teab • Noreelct • Apahl • Stoopei • Nooprt • Urnoten • Mamag • Flha Lefi • Reggie-Rullem Buet (detects radiation)

4. Radioactivity Anagrams • See if you can solve the anagrams: - • Daratiion • Teab • Noreelct • Apahl • Stoopei • Nooprt • Urnoten • Mamag • Flha Lefi • Reggie-Rullem Buet • Radiation • Beta • Electron • Alpha • Isotope • Proton • Neutron • Gamma • Half Life • Geiger-Muller Tube (detects radiation)

5. Atoms • Using the periodic table work out how many neutrons, protons and electrons and found in the following atoms: - • Hydrogen • Helium • Lithium • Carbon • Oxygen Electrons Protons and neutrons

6. Atoms Mass number 16 O O Atomic number 8 • Remember: - • The mass number (top number) shows the number of protons + neutrons • The atomic number (bottom number) shows the number of protons (and therefore, the number of electrons) • Using the periodic table work out how many neutrons, protons and electrons and found in the following atoms: - • Hydrogen • Helium • Lithium • Carbon • Oxygen

7. Periodic Table

8. Atoms Mass number O Atomic number • Remember: - • The mass number (top number) shows the number of protons + neutrons • The atomic number (bottom number) shows the number of protons (and therefore, the number of electrons) • Hydrogen: - • Mass number 1 (1 proton and 0 neutrons) • Atomic number 1 (1 proton & 1 electron) • Helium: - • Mass number 4 (2 protons and 2 neutrons) • Atomic number 2 (2 protons & 2 electrons)

9. Atoms Mass number O Atomic number • Lithium: - • Mass number 7 (3 protons and 4 neutrons) • Atomic number 3 (3 protons & 3 electrons) • Carbon: - • Mass number 12 (6 protons and 6 neutrons) • Atomic number 6 (6 protons and 6 electrons) • Oxygen: - • Mass number 16 (8 protons and 8 neutrons) • Atomic number 8 (8 protons and 8 electrons)

10. Atoms & Isotopes • An atom is made from a nucleus surrounded by electrons – the nucleus contains protons and neutrons • Isotopes are atoms that have the same number of protons, but different numbers of neutrons – the nuclei of some isotopes are unstable, emitting radiation and breaking down to form smaller nuclei…

11. Isotopes • Isotopes are the atoms of an element with different numbers of neutrons – they have the same proton number, but different mass numbers… • Look at the isotopes of hydrogen: - 1 proton; 0 neutrons; 1 electron 1 proton; 1 neutron; 1 electron 1 proton; 2neutrons; 1 electron

12. Radioactive Decay • The nuclei of some isotopes are unstable – they can split up or ‘decay’ and release radiation • Such isotopes are called radioactive isotopes or radioisotopes • When a radioactive isotope decays, it forms a different atom with a different number of protons

13. Alpha Emission • An α particle consists of 2 protons and 2 neutrons • When an unstable nucleus emits an α particle its atomic number goes down by 2, and its mass number down by 4 4 α 2

14. Beta Emission • A β particle is an electron created and emitted by a nucleus which has too many neutrons compared with protons • A neutron in its nucleus changes into a proton and a β particle – this is instantly emitted at high speed by the nucleus • The relative mass of a β particle is effectively zero, and its relative charge is -1 • When an unstable nucleus emits a β particle its atomic number goes up by 1, but its mass number stays the same (the neutron has changed into a proton) 0 β -1

15. Gamma Emission • Gamma rays are very short electromagnetic waves • Gamma rays penetrate far into materials meaning they are weakly ionising – however they are very dangerous still as they pass through materials easily so can harm from a very long distance away

16. Changing Elements • When an atom emits alpha or beta radiation, its nucleus changes – it becomes the nucleus of a different element • This is because the number of protons in the nucleus determines which element the atom belongs to – these are the changes that occur to the number of particles in an unstable nucleus when it emits a radioactive particle: -

17. Uranium • Uranium-230 nuclei emit alpha radiation and become nuclei of thorium-226 226 4 230 Th He U + 90 2 92 • The mass number is reduced by 4 (2 protons + 2 neutrons gone) • The atomic number is reduced by 2 (2 protons gone) • * The alpha particle is identical to a helium nucleus

18. Hydrogen • Hydrogen-3 nuclei emit beta radiation and become nuclei of helium-3 3 0 3 He e H + 2 -1 1 • The mass number stays the same (2 protons + 1 neutron) • The atomic number increases by 1 (1 protons added)

19. Background Radiation • Background radiation is all around us – most background radiation comes from natural sources, while most artificial radiation comes from medical examinations, such as X-ray photographs • Natural sources – radiation is all around us, coming from radioactive substances including the ground, the air, building materials and food • Radiation is also found in the cosmic rays from space

20. Background Radiation – Natural • Some rocks contain radioactive substances that produce a radioactive gas called radon.

21. Background Radiation – Artificial • Artificial sources of radiation include radioactive waste from nuclear power stations, radioactive fallout from nuclear weapons testing and medical X-rays – artificial sources account for about 15% of the average background radiation dose

22. Balancing Nuclear Equations • Alpha and beta decays can be written as nuclear equations… • *Mass and atomic numbers must balance on each side • αdecay

23. Balancing Nuclear Equations • Alpha and beta decays can be written as nuclear equations… • *Mass and atomic numbers must balance on each side • βdecay

24. Summary Questions • How many protons and neutrons are there in the nucleus of each of the following isotopes: - • C • Co • U 12 6 60 27 235 92

25. Summary Questions 238 • A substance contains the radioactive isotope U which emits alpha radiation – the product nucleus X emits beta radiation and forms a nucleus Y. How many protons and neutrons are present in the following: - • A nucleus of U • A nucleus of X • A nucleus of Y 92 238 92

26. Summary Answers • How many protons and neutrons are there in the nucleus of each of the following isotopes: - • C – 6 protons and 6 neutrons • Co – 27 protons and 33 neutrons • U – 92 protons and 143 neutrons 12 6 60 27 235 92

27. Summary Answers 238 • A substance contains the radioactive isotope U which emits alpha radiation – the product nucleus X emits beta radiation and forms a nucleus Y. How many protons and neutrons are present in the following: - • A nucleus of U – 92 protons and 146 neutrons • A nucleus of X – 90 protons and 144 neutrons (has lost 2 protons and 2 neutrons) • A nucleus of Y – 91 protons and 143 neutrons (1 neutron changed to a proton) 92 238 92