1. Decay mechanisms Exam question Radio isotopes

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3. An alpha particle is really four particles which are ejected from the nucleus of an unstable atom. An alpha particle is two protons and two neutrons. previous next smart

4. What happens when atoms of emit alpha particles? Notice that it is impossible to predict which atoms will decay but we can see that the rate of decay slows down with time. We will now look deeper inside the atom to see what is happening to the nucleus. 237 93 Np This is a model to simulate how ALPHA particles are emitted from a radioactive isotope of NEPTUNIUM. previous next smart

5. The nucleus loses 2 protons and 2 neutrons which we call an alpha particle Taking a closer look inside the NEPTUNIUM atom previous next smart

6. Before After NpPa 237 93 91 + Neptunium Palladiumalpha + previous next smart Fill in the missing numbers to complete the equation

7. Before After NpPa 237 93 233 91 + 4 2 Neptunium Palladiumalpha + previous next smart answers

8. A beta particle is simply a fast moving electron. This particle is also ejected from the nucleus of an unstable atom but the way this happens is more complicated than alpha emission. previous next smart

9. What happens when atoms emit beta particles? Notice that it is impossible to predict which atoms will decay but we can see that the rate of decay slows down with time. 233 Pa 91 We will now look deeper inside the atom to see what is happening to the nucleus. This is a model to simulate how BETA particles are emitted from a radioactive isotope of PALLADIUM. previous next smart

10. emits a beta particle when a neutron changes into a proton and an electron Taking a closer look inside the PALLADIUM atom The nucleus previous next smart

11. Before After Pa U 233 91 + 0 Palladium UraniumBeta B + previous next smart Fill in the missing numbers to balance the equation

12. Before After Pa U 233 91 233 92 + 0 Palladium UraniumBeta B + previous next smart answers

13. Gamma rays are really electromagnetic rays which are given out by the nucleus of unstable atoms. You will not need to know how this affects the nucleus of an unstable atom. previous next smart

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15. 145 144 143 142 141 140 139 138 137 136 8788899091929394 Number of neutrons Number of protons X Np 237 Pa 233 U Th 229 Neptunium-237 ( Np) is a radioactive element. The graph shows the numbers of neutrons and protons in the nuclei of the elements formed when Np decays. 237 previous next smart

16. 145 144 143 142 141 140 139 138 137 136 87888990919293 94 Number of neutrons Number of protons X Np 237 Pa 233 U Th 229 (a)Use the periodic table to identify element X. (b) Why are Pa and U considered to be different elements? 233 (c) What type of radiation is released when Np decays to form Pa? 237 233 (d) What change takes place in the nucleus when Pa changes into U? 233 previous next smart

17. 145 144 143 142 141 140 139 138 137 136 8788899091929394 Number of neutrons Number of protons X Np 237 Pa 233 U Th 229 (a)Use the periodic table to identify element X. previous next smart

18. 145 144 143 142 141 140 139 138 137 136 8788899091929394 Number of neutrons Number of protons X Np 237 Pa 233 U Th 229 (b) Why are Pa and U considered to be different elements? 233 Pa has 91 protons U has 92 protons Different proton number means different element. previous next smart

19. 145 144 143 142 141 140 139 138 137 136 8788899091929394 Number of neutrons Number of protons Np 237 Pa 233 (c) What type of radiation is released when Np decays to form Pa? 237 233 The nucleus of Neptunium has lost 2 neutrons and 2 protons. Alpha particle Neptunium nucleus Pa nucleus previous next smart

20. 145 144 143 142 141 140 139 138 137 136 8788899091929394 Number of neutrons Number of protons Np 237 Pa 233 U (d) What change takes place in the nucleus when Pa changes into U? 233 The neutron number decreases by one but the proton number increases by one A neutron changes into a proton and an electron previous next smart

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22. previous next smart An isotope is an atom which has the same number of protons but a different number of neutrons The underlined phrases score the marks---so learn this definition off by heart

23. X A Z C 12 6 H 1 1 Li 7 3 Symbol of the element Nucleon number Proton number previous next smart

24. You should know what an isotope is What a radio-isotope is and give some examples. previous next smart

25. HHH previous next smart Write in the missing numbers (the bottom one is the number of protons) (the top one is the protons and neutrons)

26. H 1 1 H 2 1 H 3 1 previous next smart answers

27. He previous next smart

28. He 4 2 3 2 previous next smart answers

29. C 12 6 C 14 6 Now lets have a closer look at the nuclei of these isotopes. previous next smart

30. CCN Carbon-12 is stable but Carbon-14 is unstable (a radio-isotope). Carbon-14 emits a beta particle and decays to become nitrogen previous next smart Count the particles in these nuclei after the beta particle is emitted and fill in the numbers

31. C 12 6 14 7 N Carbon-12 is stable but Carbon-14 is unstable (a radio-isotope). Carbon-14 emits a beta particle and decays to become nitrogen previous next smart answers

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