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Nuclear Reactions Alpha, Beta, and Gamma Decay. State what is meant by alpha, beta and gamma decay of radionuclides. Identify the processes occurring.

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Presentation on theme: "Nuclear Reactions Alpha, Beta, and Gamma Decay. State what is meant by alpha, beta and gamma decay of radionuclides. Identify the processes occurring."— Presentation transcript:

1 Nuclear Reactions Alpha, Beta, and Gamma Decay

2 State what is meant by alpha, beta and gamma decay of radionuclides. Identify the processes occurring in nuclear reactions written in symbolic form.

3 The Atom The atom consists of two parts: 1. The nucleus which contains: 2. Orbiting electrons. protons neutrons

4 All matter is made up of elements (e.g. carbon, hydrogen, etc.). The smallest part of an element is called an atom. Atom of different elements contain different numbers of protons. The mass of an atom is almost entirely due to the number of protons and neutrons. The Atom

5 X A Z Mass number Atomic number Element symbol = number of protons + number of neutrons = number of protons

6 X A Z A = number of protons + number of neutrons Z = number of protons A – Z = number of neutrons Number of neutrons = Mass Number – Atomic Number

7 U U There are many types of uranium: A Z Number of protons Number of neutrons A Z Number of protons Number of neutrons

8 U U There are many types of uranium: Isotopes of any particular element contain the same number of protons, but different numbers of neutrons. A235 Z92 Number of protons92 Number of neutrons143 A238 Z92 Number of protons92 Number of neutrons146

9 Most of the isotopes which occur naturally are stable. A few naturally occurring isotopes and all of the man- made isotopes are unstable. Unstable isotopes can become stable by releasing different types of particles. This process is called radioactive decay and the elements which undergo this process are called radioisotopes/radionuclides.

10 Radioactive decay results in the emission of either: an alpha particle (  ), a beta particle (  ), or a gamma ray  Radioactive Decay

11 An alpha particle is identical to that of a helium nucleus. It contains two protons and two neutrons. Alpha Decay

12 X A Z Y A - 4 Z He 4 2 Alpha Decay unstable atom more stable atom alpha particle

13 Alpha Decay Ra Rn He 4 2

14 X A Z ? A - 4 Z He 4 2 Ra Rn He 4 2 Alpha Decay

15 Rn He Po He 4 2 Rn ? A Z He 4 2 Alpha Decay

16 ? A Z + Th He 4 2 Alpha Decay

17 He 4 2 U Th He 4 2

18 Th ? A Z He 4 2 Alpha Decay

19 He Ra He 4 2 Th

20 ? A Z + Pb He 4 2 Alpha Decay

21 He Pb He 4 2 Po

22 Beta Decay A beta particle is a fast moving electron which is emitted from the nucleus of an atom undergoing radioactive decay. Beta decay occurs when a neutron changes into a proton and an electron.

23 Beta Decay As a result of beta decay, the nucleus has one less neutron, but one extra proton. The atomic number, Z, increases by 1 and the mass number, A, stays the same.

24 Beta Decay Po  0 At

25 ? A Z ? A Z  0 Beta Decay Po Rn  0

26 Th ? A Z +  0 Beta Decay Th Pa  0

27 ? A Z Pb  0 Beta Decay

28 Tl Pb  0

29 Bi ? A Z +  0 Beta Decay

30 Bi Po  0

31 ? A Z Bi  0 Beta Decay

32 Pb Bi  0

33 Gamma Decay Gamma rays are not charged particles like  and  particles. Gamma rays are electromagnetic radiation with high frequency. When atoms decay by emitting  or  particles to form a new atom, the nuclei of the new atom formed may still have too much energy to be completely stable. This excess energy is emitted as gamma rays (gamma ray photons have energies of ~ 1 x J).


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