1. U 238 92 Nuclear Symbols A t o m i c M a s s A t o m i c N u m b e r
T h e e l e m e n t i s r e p r e s e n t e d
b y i t s c h e m i c a l s y m b o l

2. Spontaneous Radioactive Decay
Most particles are ejected from the nucleus
At high speeds…
Radioactive decay always involves changes in protons and neutrons (sometimes electrons)

3. e e n He Nuclear Particles 4 alpha 2 Beta (electron)
beta-plus (positron)
neutron He -1 e e +1 n 1
continued

4. alpha, beta, and gamma
These three forms of radiation can be distinguished by a magnetic field since
the positively-charged alpha particles curve in one direction,
the negatively-charged beta particles curve in the opposite direction,
and the electrically-neutral gamma radiation doesn't curve at all.

5. Ionizing radiation – interacts with atoms and biological molecules, like DNA, and turns atoms into ions by interacting with electrons and disrupting chemical bonds

7. In this kind of decay, a proton disintegrates and becomes a neutron and a low-mass positively charged positron fires out of the nucleus!

8. Nuclear equations are balanced much like chemical equations.

9. To balance nuclear equations, follow these two rules:
- mass number is conserved
- electric charge is conserved

10. Rule One Mass number is conserved: The sum of the mass
numbers before the
change must equal the
sum of the mass numbers
after the change.

11. Rule Two Charge is conserved: The total electric charge on subatomic
particles and nuclei
before and after the
change must be equal.

12. Nuclear Particles
alpha
continued

13. Nuclear Particles 4 2
alpha He
continued

14. Nuclear Particles
beta
continued

15. Nuclear Particles
beta -1 e
continued

16. Nuclear Particles
beta-plus
(positron)
continued

17. Nuclear Particles
beta-plus e +1
continued

18. Nuclear Particles
neutron
continued

19. Nuclear Particles
neutron n 1
continued

20. Nuclear Particles
proton
continued

21. Nuclear Particles 1
proton H
continued

22. Add 1 Daughter Particle He Li + H 4 7 1 2 3 Alpha decay simulation

23. Add 1 Daughter Particle He Li + H He + He Li + H 4 7 1 2 3 4 4 7 1 2 2

24. Add 1 Daughter Particle He Li + H He + He Li + H Li + 2 He H 4 7 1 2 3

25. Add 1 Daughter Particle 3 1 2 1 1
n +
H + H

26. n + H + H n + H + H Add 1 Daughter Particle He 3 1 2 1 1 3 1 2 1 1 4 2
n +
H + H 3 1 2 1 1 4 2
n + He
H + H
This fusion of hydrogen isotopes happens on the Sun, stars, and thermonuclear explosions!

27. Alpha Decay

29. What particle is ejected from the unstable nucleus of carbon-14?6 14 7
N + C
Describe what happens to the nucleus…

30. Add 1 Daughter Particle 14 6 14 7
N + C 14 6 14 7
N + -1 C e
Beta!

31. Beta Decay

33. Two More Types…Are you kidding?
Positron Decay – opposite of a beta particle
Electron capture or K – capture

34. Add 1 Daughter Particle
208 82 4 2 1
n +
Pb + 4 He 4

35. n + Pb + 4 He 4 Th n + Pb + 4 He 4 Add 1 Daughter Particle 208 82 4 2
n +
Pb + 4 He 4
208 82
220 90 4 2 1 Th
n +
Pb + 4 He 4

36. K-capture An atomic nucleus captures an electron from its own
Nuclear Particles
K-capture
An atomic nucleus captures
an electron from its own
innermost energy level.
continued

37. K-capture The atomic number is decreased by one and the
Nuclear Particles
K-capture
The atomic number is
decreased by one and the
mass number remains
the same.
continued

38. Nuclear Particles
K-capture
100 44
Ru +

39. Add 1 Daughter Particle -1
100 44 e
Ru +

40. Add 1 Daughter Particle -1
100 44 e
Ru + -1
100 44 e
100 43 Tc
Ru +

41. Nuclear Particles
K-capture -1
100 43
100 44
Ru + e Tc

42. You Try! Complete the worksheet on balancing nuclear equations.
Can you describe what is happening to the nuclear particles with each type of nuclear change? You should.

43. Strontium-90 Spark
Strontium-90 is a radioactive isotope that decays via a beta particle. It has a half-life of 28.8 years. Chemically it behaves like calcium and will be absorbed into bones but will potentially lead to bone cancer or leukemia. Write the decay equation for Sr-90 and determine how much of a 100 gram sample would remain after about 86 years.
It comes from spent nuclear fuel after uranium nuclei split and if ingested most is excreted in the urine.

44. Radioisotope
Half-life
Polonium-215
seconds
Bismuth-212
60.5 seconds
Sodium-24
15 hours
Iodine-131
8.07 days
Cobalt-60
5.26 years
Radium-226
1600 years
Uranium-238
4.5 billion years

45. Decay Series of U-238