1. Houghton Mifflin Company and G. Hall. All rights reserved. 1 The Nucleus Now, we take a look at the nucleus where the protons and neutrons reside. Breaking these apart can cause a large release of energy.

2. Houghton Mifflin Company and G. Hall. All rights reserved. 2 Table 24.1

3. Houghton Mifflin Company and G. Hall. All rights reserved. 3 Fig. 24.1 Three types of particles.

4. Houghton Mifflin Company and G. Hall. All rights reserved. 4 Shielding

5. Houghton Mifflin Company and G. Hall. All rights reserved. 5 Nuclear Nomenclature  Nuclides need to know the symbols for protons and neutrons and how they add up to form isotopes (same atomic number, different atomic mass) H (hydrogen), D (deuterium), T (tritium).  Nuclide designation:   where E is the element, A is the mass number = number of protons + neutrons (isotope), and Z is the atomic number (number of protons).  Also, we sometimes write the isotope as Fe-55, Co-60, Pb-206, etc. In the nucleus, the protons and neutrons are called nucleons.

6. Houghton Mifflin Company and G. Hall. All rights reserved. 6 A = sum of neutrons and protons i.e. isotope. Z = number of protons. N = number of neutrons.

7. Houghton Mifflin Company and G. Hall. All rights reserved. 7 A Z N A = sum of neutrons and protons i.e. isotope. Z = number of protons. N = number of neutrons.

8. Houghton Mifflin Company and G. Hall. All rights reserved. 8 Alpha (  ) particle emission notice both sides equal with mass and atomic number.

9. Houghton Mifflin Company and G. Hall. All rights reserved. 9 Beta (  ) particle emission

10. Houghton Mifflin Company and G. Hall. All rights reserved. 10 Gamma ray (  ) emission, atom is radioactive m is for metastable state.  ray is electromagnetic radiation i.e. photon.

11. Houghton Mifflin Company and G. Hall. All rights reserved. 11 Positron ( + e) emission (electron with positive charge i.e. anti matter)

12. Houghton Mifflin Company and G. Hall. All rights reserved. 12 Electron capture In the nucleus, a proton and electron react.

13. Houghton Mifflin Company and G. Hall. All rights reserved. 13 Fig. 24.2

14. Houghton Mifflin Company and G. Hall. All rights reserved. 14 Prob. 24.1

15. Houghton Mifflin Company and G. Hall. All rights reserved. 15 Radioactive Decay

16. Houghton Mifflin Company and G. Hall. All rights reserved. 16 Radioisotope dating  We can use the first order rate law and decay of certain isotopes to determine how old certain objects are. This method is used extensive for radiocarbon dating which is based on the decay of 14 C.

17. Houghton Mifflin Company and G. Hall. All rights reserved. 17 Rate of Decay Rate (A) = kN The rate of decay is proportional to the number of nuclides. This represents a first-order process. The SI unit of radioactivity is the becquerel (Bq). A larger unit is the curie (Ci) = 3.7E10 d/s.

18. Houghton Mifflin Company and G. Hall. All rights reserved. 18 Half-Life...the time required for the number of nuclides to reach half the original value (N 0 /2).

19. Houghton Mifflin Company and G. Hall. All rights reserved. 19 Radiodating  This first order decay is very helpful in carbon or other datings. ln (A t /A o ) = - t. You can see that if we know the N at various times, we can determine t the age of an object provided that the half-life is not to long or to short.  In the upper atmosphere, the reaction takes place due to cosmic radiation that results in neutrons. The nuclear reaction:

20. Houghton Mifflin Company and G. Hall. All rights reserved. 20

21. Houghton Mifflin Company and G. Hall. All rights reserved. 21 Carbon-14 Dating

22. Brigham Young researcher Scott Woodward taking a bone sample for carbon-14 dating at an archeological site in Egypt.

23. Houghton Mifflin Company and G. Hall. All rights reserved. 23 Fig. 24.4

24. Houghton Mifflin Company and G. Hall. All rights reserved. 24 Table 24.5

25. Houghton Mifflin Company and G. Hall. All rights reserved. 25 Radiation Units

26. Houghton Mifflin Company and G. Hall. All rights reserved. 26 Table 24.7

27. Houghton Mifflin Company and G. Hall. All rights reserved. 27

28. Houghton Mifflin Company and G. Hall. All rights reserved. 28 Fig. 24.13

29. Houghton Mifflin Company and G. Hall. All rights reserved. 29 Energy and Mass related to radioactive decay of uranium  m = mass defect  E = change in energy If  E =  (exothermic), mass is lost from the system. When a system gains or loses energy it also gains or loses a quantity of mass.  E =  mc 2

30. Houghton Mifflin Company and G. Hall. All rights reserved. 30 Fig. 24.16

31. Houghton Mifflin Company and G. Hall. All rights reserved. 31 Nuclear waste storage (2 Engineers)

32. Houghton Mifflin Company and G. Hall. All rights reserved. 32 Fig. B24.1

33. Houghton Mifflin Company and G. Hall. All rights reserved. 33 Lecture summary  Know the different types of radiation.  Decay of different radiation.  Rate law and its use in radiodating.  Radioisotopes are used extensively in medicine and in industrial applications.  Radiation is safe provided the proper safety measures are taken.

34. Houghton Mifflin Company and G. Hall. All rights reserved. 34 Notes  Please check the class website  www.rutchem.rutgers.edu www.rutchem.rutgers.edu  For further developments such as practice exam and exam notes.  Have a safe and pleasant summer.