PSC 4010

1. PSC 4010 Nuclear Technology: A matter of Energy

2. PSC 4010: Chapter 4 Goals: _ SWBAT classify examples of changes in matter (physical, chemical, nuclear) _SWBAT distinguish between different nuclear reactions (radioactivity, fission, fusion) _SWBAT compare the nature, speed, electric charge and penetrating power of alpha and beta particles, as well as gamma rays (and X rays). Also, to know how each can affect matter _SWBAT calculate the decay time for an isotope given its half-life _SWBAT identify the radioactive element involved, the type of radiation emitted and the new element formed for a given decay process _ SWBAT understand the relationships between energy released in a nuclear reaction, mass defect, and stability of resulting isotope

3. PSC 4010: Chapter 4 Changes in matter can be: (Table on page 2.37) • Physical (appearance) • Chemical (electrons in last shell) • Nuclear (nucleus)

4. PSC 4010: Chapter 4 Physical changes (p. 4.3 – 4.7): • Superficial change • Needs little amount of energy • DOES NOT change nature of element or compound • DOES NOT affect the properties of element or compound • Changes state of matter

5. PSC 4010: Chapter 4 Physical changes: Practice Exercise Page 4.7, Ex. 4.2

6. PSC 4010: Chapter 4 Chemical changes (p. 4.8 – 4.12): • More profound change • Needs more energy • Involves electrons in last shell • NEW SUBSTANCES are formed • Evidences of chemical change: _change of color _gas release _formation of precipitate _change of temperature

7. PSC 4010: Chapter 4 Chemical changes: Practice Exercise Page 4.9, Ex. 4.4

8. PSC 4010: Chapter 4 Chemical changes: Ionization: when an atom gains or loses one or more electrons Page 4.11, Figure 4.3

9. PSC 4010: Chapter 4 Chemical changes: Practice Exercise Page 4.12, Ex. 4.6

10. PSC 4010: Chapter 4 Nuclear changes (p. 4.13 – 4.16): • Most profound change • Needs much more energy • Involves particles in nucleus! • An element is changed into another • ALL involve emission of radiation (which can be harmless, dangerous, or lethal)

11. PSC 4010: Chapter 4 Radioactivity (natural): (p. 4.17 – 4.37) • spontaneous nuclear change • nucleus of a very large and unstable isotope disintegrates into a lighter and more stable element • emits radiation in the form of particles (alpha and beta) and in the form of energy (gamma rays)

12. PSC 4010: Chapter 4 Radioactivity emissions: (Table 4.2 on page 4.21)

13. PSC 4010: Chapter 4

14. PSC 4010: Chapter 4 Radiation in an electric field: (Figure 4.7 on page 4.20)

15. PSC 4010: Chapter 4 Nature of radiations(waves) (p. 4.23 – 4.25): _Gamma rays are electromagnetic waves (like light), and therefore they behave as if they have no mass, they are just radiation (energy) _Gamma and X-rays have highest frequencies, and energies of the whole electromagnetic spectrum. Therefore they are called IONIZING RADIATIONS _Our eyes only see the colors contained in the narrow visible part of said spectrum

16. PSC 4010: Chapter 4 Nuclear changes: Practice Exercises Page 4.22, Ex. 4.12 – 4.16

17. PSC 4010: Chapter 4 Nature of radiations(particles) (p. 4.25 – 4.27): _Alpha and Beta particles have a mass (particles) _Alpha particles are very heavy compared to Beta particles, and both more than Gamma rays (massless) _Alpha and Beta particles can physically remove electrons from atoms. Therefore they are also considered IONIZING RADIATIONS

18. PSC 4010: Chapter 4 Nuclear changes: Practice Exercises Page 4.27, Ex. 4.18 – 4.20

19. PSC 4010: Chapter 4 Uranium-238 decay chain (p. 4.27 – 4.32): _Transmutation: Process by which an unstable radioactive element transforms into a more stable one _During each step of the transmutation Alpha, Beta and Gamma rays (or neutrons) are emitted _During the transmutation there is CONSERVATION OF MASS (number of protons and neutrons is the same before and after transmutation)

20. PSC 4010: Chapter 4 Uranium-238 decay chain (p. 4.27 – 4.32): Transmutation of an Alpha particle • Emission of alpha particles (2 protons, 2 neutrons) • Mass number decreases by four (2 protons + 2 neutrons) • Atomic number decreases by two (2 protons) Ex:

21. PSC 4010: Chapter 4 Uranium-238 decay chain (p. 4.27 – 4.32): Transmutation of an Beta particle • Emission of beta particles (1 electron) • Mass number DOES NOT change • Atomic number increases by one (1 neutron is converted into 1 proton) Ex:

22. PSC 4010: Chapter 4 Nuclear changes: Practice Exercise Page 4.31, Ex. 4.25

23. PSC 4010: Chapter 4 Half-life of radioactive isotopes (p. 4.32 – 4.37): _Half-life of radioactive isotopes: Time it takes to lose half of its mass Ex: Iodine-131 has a half-life of 8 days. Therefore, if you have 40kg, _after 8 days you end up with 20kg _after 8 more days (16) you end up with 10kg _after 8 more days (24) days you end up with 5kg _after 8 more days (32) you end up with 2.5kg _after 8 more days (40) s you end up with 1.25kg _after 8 more days (48) you end up with 0.625kg _and so on until it is completely transformed _The longer the half-life, the lower the emissive radiation (and vice versa) _U-238 has a half-life of 4.5 billion years!

24. PSC 4010: Chapter 4 Nuclear changes: Practice Exercise Page 4.35, Ex. 4.29

25. PSC 4010: Chapter 4 Transmuting matter (p. 4.38 – 4.40): _Natural transmutations are natural radioactivity, or spontaneous transformation of unstable elements (Rutherford demonstration) _Artificial transmutations are forced transmutations produced in a laboratory or man-made environment (NOT spontaneous) Ex: Cobalt-60 and Iodine-131 are artificially made radioactive isotopes widely used in medicine

26. PSC 4010: Chapter 4 Nuclear Fission (p. 4.40 – 4.44): _Fission: to break into smaller parts _Nuclear Fission: Atoms nuclei broken into smaller atoms (bombarding nuclei with particles, usually neutrons) _Nucleus split as a result of fission, produces LOTS of radiation emission and Large amounts of energy released _These nuclear fission reactions can sometimes be considered chain reactions, as they produced more neutrons that will in turn split more nuclei of the same element _Chain reactions can be used to produced electricity for millions of people or just used to produce BOMBS

27. PSC 4010: Chapter 4 Nuclear Fusion (p. 4.44 – 4.45): _Nuclear Fusion: Opposite to fission, two smaller elements combine to produce a bigger and heavier one _Nuclei fusing together produces EVEN MORE energy that Fission (3 to 3.5 times for same amount of fuel) _Nuclear Fusion is how the Sun creates its energy! _Nuclear Fusion is feasible for light elements (H or He) but nearly impossible for heavier elements since these reactions require temperature values of MILLIONS degrees, and extremely high pressure. _Because of the extreme experimental conditions, nuclear fusion is also known as Thermonuclear reactions

28. PSC 4010: Chapter 4 Nuclear changes: Practice Exercise Page 4.45, Ex. 4.39 Page 4.46, Ex. 4.40

29. PSC 4010: Chapter 4 Energy involved in nuclear changes (E = mc2) (p. 4.46 – 4.49): Nuclear forces are extremely powerful, BUT can only work at small distances. That is why bigger nuclei are unstable. • Chemical change produce high amounts of energy • Nuclear Fission produces ONE MILLION times the amount of energy of a chemical reaction with the same amount of fuel • Nuclear Fusion produces up to THREE MILLION times the amount of energy of a chemical reaction with the same amount of fuel

30. PSC 4010: Chapter 4 Mass defect (p. 4.47 – 4.49): Mass defect is the difference between the mass of the protons and neutrons by separate, and the mass of the resulting nucleus. The difference of mass is converted to Energy • The greater the mass defect, the greater the amount of energy released! • Every nuclear reaction involves the generation of a new nuclei as elements transmute into others. This means that at each step of a decay chain, energy is released as a consequence of mass defect

31. PSC 4010: Chapter 4 Practice Exercises for Chapter 3: • Page 4.53 – 4.60 – Ex 4.45 – 4.69