Nuclear Decay

1. Nuclear Decay Graphic: www.lab-initio.com

2. Nuclear Symbols Mass number, A (p+ + no) Element symbol Atomic number, Z (number of p+)

3. Balancing Nuclear Equations Areactants = Aproducts 235 + 1 = 142 + 91 + 3(1) 92 + 0 = 56 + 36 + 3(0) Zreactants = Zproducts

4. Balancing Nuclear Equations #2 222 226 = 4 + ____ 222 Rn 86 86 88 = 2 + ___ Atomic number 86 is radon, Rn

5. Balancing Nuclear Equations #3 95 235 + 1 = 139 + 2(1) + ____ 95 Y 39 39 92 + 0 = 53 + 2(0) + ____ Atomic number 39 is yttrium, Y

6. Alpha Decay Alpha production (a): an alpha particle is a helium nucleus Alpha decay is limited to heavy, radioactive nuclei

7. Alpha Radiation Limited to VERY large nucleii.

8. Beta Decay Beta production (b): A beta particle is an electron ejected from the nucleus Beta emission converts a neutron to a proton

9. Beta Radiation Converts a neutron into a proton.

10. Gamma Ray Production Gamma ray production (g): Gamma rays are high energy photons produced in association with other forms of decay. Gamma rays are massless and do not, by themselves, change the nucleus

11. Gamma Ray Production Gamma ray production (g): Gamma rays are high energy photons produced in association with other forms of decay. Gamma rays are massless and do not, by themselves, change the nucleus

12. Positron Production Positron emission: Positrons are the anti-particle of the electron Positron emission converts a proton to a neutron

13. Electron Capture Electron capture: (inner-orbital electron is captured by the nucleus) Electron capture converts a proton to a neutron

14. Types of Radiation

15. NuclearStability Decay will occur in such a way as to return a nucleus to the band (line) of stability. The most stable nuclide is Iron-56 If Z > 83, the nuclide is radioactive Graphic – Wikimedia user : Napy1kenobi

16. A Decay Series A radioactive nucleus reaches a stable state by a series of steps Graphic – Wikimedia Commons User Tosaka

17. Half-life Graphic - http://cafreetextbooks.ck12.org/science/CK12_Earth_Science_rev.pdf

18. Decay Kinetics Decay occurs by first order kinetics (the rate of decay is proportional to the number of nuclides present) N0 = number of nuclides present initially N = number of nuclides remaining at time t k = rate constant t = elapsed time

19. Calculating Half-life t1/2 = Half-life (units dependent on rate constant, k)

20. Sample Half-Lives