Содержание
- 2. Chapter I 1.1 nuclear Structure 1.2 Some properties of nuclei 1.3 Size of nuclei 1.4 Nuclear
- 3. Chapter III Nuclear Force 3.1 Short Range 3.2 Repulsion core 3.3 Charge dependent 3.4 Semi empirical
- 4. Nuclear Structure Atoms consist of electrons in orbit about a central nucleus. As we have seen
- 5. The nucleus of an atom consists of neutrons and protons, collectively referred to as nucleons. The
- 6. Any nucleus is specified by its atomic number (Z)(no. of protons) and its mass number (A)(total
- 7. Materials are classified into :
- 9. Some Properties of Nuclei All nuclei are composed of two types of particles: neutrons and protons.
- 10. Furthermore, a survey of the stable nuclei reveals that even-even nuclei are the ones most abundant
- 11. Rutherford's experiment Principle of Rutherford's experiment. By bombarding a very thin gold foil with alpha particles,
- 14. Alpha backscattering on nucleus Rutherford observed the backward bounce of some alpha particles as projectiles sent
- 15. The Size of Nuclei Rutherford found an expression for how close an alpha particle moving directly
- 17. Thus, the radius of the gold nucleus must be less than this value. For silver atoms,
- 18. Calculation of Nuclear Radius The nuclear radius (R) is considered to be one of the basic
- 19. Most nuclei are approximately spherical and have an average radius given by R = r0 A1/3
- 20. where A is the total number of nucleons and r0 is a constant equal to 1.2
- 21. It is well known that lead and oxygen contain different atoms and that the density of
- 22. The volume V of the nucleus is approximately spherical and has a radius R, so that
- 24. The stable nucleus with the largest number of Protons (Z = 83) is that of bismuth,
- 25. Two positive charges that are as close together as they are in a nucleus repel one
- 26. so a different type of force must hold the nucleus together. This force is the strong
- 27. Many features of the strong nuclear force are well known. For example, it is almost independent
- 28. The limited range of action of the strong nuclear force plays an important role in the
- 29. As in Fig. shows a plot of N versus Z for naturally occurring elements that have
- 31. As more and more protons occur in a nucleus, there comes a point when a balance
- 32. All nuclei with more than 83 protons (e.g., uranium, Z=92) are unstable and spontaneously break apart
- 34. Some isotopes don’t occur naturally, but can be produced in the laboratory through nuclear reactions. Isotones:
- 35. The basic properties of the atom constituents can be summarized as follows:
- 36. Spin: Each of the atomic constituents has spin ½ h and is an example of what
- 37. Charge and Mass The proton carries a single positive charge e = 1.602 177 33 x
- 38. Table 1
- 40. The Mass Defect of the Nucleus and Nuclear Binding Energy Because of the strong nuclear force,
- 41. Energy, called the binding energy, must be supplied to break the nucleus apart into its constituent
- 42. It would be found that the total mass of the atom is less than the sum
- 43. Δ = (Z)(Mp) + (Z)(Me) + (A-Z)(Mn) - Ma where: Δ = mass defect Z =
- 45. To see how the nuclear binding energy varies from nucleus to nucleus, it is necessary to
- 46. rapidly for nuclei with small masses and reaches a maximum of approximately 8.7 MeV/ nucleon for
- 47. For example, consider an isotope of Lithium, Li: A = 7, Z = 3, M =
- 48. plot of binding energy per nucleon versus the nucleon number
- 52. Radioactivity When an unstable or radioactive nucleus disintegrates spontaneously, certain kinds of particles and/or high energy
- 53. α and β rays are deflected by a magnetic field
- 54. Alpha particles (α) (+ve charge, helium nuclei He). Beta particles (β) (-ve charge, electrons). Gamma ray
- 55. Radioactive Decay Law
- 56. Half-life (τ)
- 58. The activity of a radioactive sample is the number of disintegrations per second that occur. Each
- 60. Example: Iodine 131 is used in the treatment of thyroid (الغدة الدرقية ) disorders. Its half-life
- 61. Problems After 24 hours the radioactivity of a nuclide is one-eighth times its original level. What
- 62. Alpha Decay The nucleus may emit a fast, massive particle that contains two protons and two
- 63. Beta Decay The nucleus may emit a fast electron. Since there is reason to believe that
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