1. Bell Work: Radioactivity
What two particles have mass and are found in the nucleus?
The ( proton / neutron / electron ) is the atomic number.
_____ rays are given off in nuclear reactions.
In fission, the atom(s) ( is split / are combined ).
Elements are arranged on the _____ table.

2. RADIOACTIVITY!! N

3. Atomic #: number protons
Mass #(Atomic Mass): protons + neutrons

4. Atomic Mass: protons + neutrons Atomic #: protons
Average Atomic Mass averages all the isotopes of an element
Atomic #:
protons

6. GAMMA What is Radioactivity?
Spontaneous emission of rays and particles from the nucleus of an unstable nucleus.
Elements with atomic numbers greater than 82 are all radioactive.
Radioactivity is the result of nuclear reactions: can also emit particles
(alpha and beta)
GAMMA

7. Nuclear Symbols Mass number (p+ + no) Element symbol Atomic number
(number of p+)

8. Types of Radioactive Decay4
alpha production (a): helium nucleus
beta production (b): a neutron becomes a proton and an electron is emitted 2+ He 2
Notice how the mass on both sides of the  is equal
Notice how the proton number on both sides of the  is equal - 1 e
Notice how the mass on both sides of the  is equal
Notice how the proton number on both sides of the  is equal

9. What happens to the atomic nucleus?
An atom of one element becomes an atom of another - TRANSMUTATION
Why?
An element’s identity is defined by the particles in the nucleus – change the nucleus, change the element
No other reaction causes transmutation

10. Alpha Radiation Limited to VERY large nucleii.
Notice how the mass before and after is equal
Notice how the proton number before and after is equal

11. Beta Radiation Converts a neutron into a proton.
Notice how the mass before and after is equal
Notice how the proton number before and after is equal
Beta Radiation
Converts a neutron into a proton.
The atomic number increases by 1.

12. Energy and Mass
Nuclear changes occur with small but measurable losses of mass. The lost mass is called the mass defect, and is converted to energy according to Einstein’s equation:
DE = Dmc2
Dm = mass defect
DE = change in energy
c = speed of light
Because c2 is so large, even small amounts of mass are converted to enormous amount of energy.

13. Types of Radioactive Decay
gamma ray production (g):

14. Types of Radiation

15. A radioactive nucleus reaches a stable state by a series of steps
A Decay Series

16. Half Life Each radioactive element undergoes
radioactive decay emitting particles
and/or energy.
The time it takes for this decay to occur is half-life.

18. Half-life Time it takes for ½ the radioactive substance to decay
Arsenic-74 has a half-life of 17.9 days. If you start with 100 grams of As-74, how much will be left after 53.7 days?
Number half lives
Time
(days)
Amount left (g)
100
Number half lives
Time
(days)
Amount left (g)
Number half lives
Time
(days)
Amount left (g)
100 1
17.9 50 2
35.8 25 3
53.7
12.5
Number half lives
Time
(days)
Amount left (g)
100 1
17.9 50 2
35.8 25
Number half lives
Time
(days)
Amount left (g)
100 1
17.9 50

19. Fission and Fusion alternative energy sources.

20. Nuclear Fission and Fusion
Fusion: Combining two light nuclei to form a heavier, more stable nucleus.
Fission: Splitting a heavy nucleus into two nuclei with smaller mass numbers.

21. Fission

22. A Fission Reactor

23. Fusion

24. Fusion- The energy of tomorrow?