1. Auburn High School Nuclear Chemistry
The study of nuclear change.
Some elements undergo chemical changes in their nucleus that alters their number of protons or neutrons.
(yes, before we said that protons can’t be changed but this is newer technology and discovery. If you change the number of protons, you change the element)

2. Nucleus nucleus contains nucleons atomic mass, a.k.a. mass number
p+ and n0
atomic mass, a.k.a. mass number
protons + neutrons
atomic number
# protons
identifies the element

3. Isotopic notation
Symbol
Mass
Atomic
number

4. Same number of protons but different number of neutrons

5. An element is considered radioactive because it releases Energy
Transmutation
Sometimes the changes in the nucleus are such that an element is transformed into a different element
change in atomic number
An element is considered
radioactive because it releases Energy
during transmutation

6. Artificial Natural Transmutation Transmutation
Change in nucleus occurs when bombarded by an alpha particle or neutron
2 in reactant
2713Al + 42He P + 10n
Change in nucleus occurs spontaneously
ONLY one reactant is the atom undergoing transmutation
23994Pu U + 42He

7. Remember- you always need to conserve
Notice the atomic mass and atomic numbers on both sides are equal
2713Al + 42He P + 10n
23994Pu U + 42He

8. FUSION Two elements JOIN to become one new element
EXTREMELY Large quantities of E are released when smaller nuclei are combined to form larger nuclei
Occurs at very high temperatures
Power of the sun and stars

9. Fusion
Look for:
Two small elements combine to make a larger element

10. Hydrogen becomes helium
Deuterium
Tritium

11. Nuclear Fission
Splitting an atom – one element goes to Two or more elements

12. The energy produced in a times greater than the E
fission reaction is 1,000,000
times greater than the E
produced in a chemical reaction

13. Splitting one atom doesn’t provide a lot of energy but if . . .
Chain Reaction

14. Fission
Look for:
One heavy element and a neutron collide to create 2 smaller elements and 3 neutrons

15. Nuclear Power Plants Nuclear power plants UO2 pellets as fuel
uses 3% U-235
A controlled chain reaction occurs in the fuel rods to create E
To slow and control a reaction- cool it
Weapons grade U is 90%
U-235
Uncontrolled
chain reaction

18. Reactor= holds control rods filled with uranium
Reactor= holds control rods filled with uranium. Has cold water circulating to control reaction
Condensor=Creates steam to turn the turbine which creates elecricity from spinning magnets around copper with
Pump = cold water cools the condensor and water around the reactor
Containment shell- Thick concrete to shiel the environment from radiation

20. Stability of Nuclei Most nuclei are stable
some elements have unstable isotopes
Radioisotopes- have more neutrons than they should
Ex. C-12 stable and won’t transmutate
C-14 unstable and will transmutate

21. What causes instability?
As atoms increase in size the ratio of neutrons to protons also increases
the larger the ratio of Neutrons to Protons the more unstable the atom (more neutrons = unstable)
All nuclei with atomic numbers > 83 are unstable and radioactive

22. Types of Radiation
Types of radiation emitted from the nucleus during transmutation
THESE ARE ON TABLE O and N

23. alpha particles Alpha particle – A Helium atom
WEAK form of radiation with very little penetrating power. Often cannot penetrate through your skin.
alpha particles He or

24. Beta particles Beta particles – the nucleus ejects an electron
a neutron breaks apart into a proton and an electron. The electron is emitted from the nucleus
Beta decay

25. e Positron Radiation +1 ß++1
Positron Radiation ß+
Positron – a positive electron is emitted from the nucleus
X = 3718Ar isotope

26. Neutrons= n
Protons = 11 H ( H+ Ion)

27. Gamma Radiation
energy usually released as a result of a nuclear decay.
It has the STRONGEST penetrating power of all the radiation types

28. Radiation Penetration

29. Radiation risks Can cause mutations
High exposure can lead to serious illness or injury.
Spent fuel rods from power plants are still radioactive for thousands of years.
Thermal pollution from water dumped into streams or lakes by power plant.
if there is a meltdown and radiation is released (ex Chernobyl in the Ukraine in 1986.) Farmland is unusable for generations, unsafe for people to live in the area.
Nuclear weapons destroy everything

30. Severe low WBC / lesions
Dose (rem)
Effects
0 - 25
No observable effects
Decreased WBC count
Severe low WBC / lesions
Radiation burns
Internal bleeding
50% death in few weeks
> 700
DEATH

31. Effects of radiation from the Chernobyl nuclear accident

33. Hiroshima

34. People burned into the landscape

35. Radiation burns and clothing patterns burned onto skin

36. Those cells that undergo rapid mitosis (cell division) are more sensitive to radiation.
Bone marrow:Cells that make blood cells
“Pre” sperm & egg cells
Lung tissue
Digestive lining
eyes

37. Benefits of radiation
Radioisotopes are used in diagnosing and treating cancer
I-131
diagnose thyroid disorders
Co-60
treat cancer
Short half lives
decay quickly

38. Produce LOTS of elecritcity
Smoke detectors Am Am
Carbon – 14 dating to determine age of ancient materials
U-238 date the earth

39. In 1991 the Iceman was discovered
In 1991 the Iceman was discovered. Less than 50% of the C-14 atoms had decayed.
T = 5730 y
the age of the Iceman was determined to be approximately 5300 years old.
Carbon Dating

40. C-14 is NOT used to date the Earth. WHY?
C-14 has too short of a half life
Found in organic materials
U-238
date the age of the earth
T = 4.5x109 y
Found in rocks

41. 1/2 life
Time it takes for 1/2 of the atoms
in a sample to decay.

42. Table N 1/2 lives are always constant
1/2 lives are different for different radioisotopes (nuclides)
An atom with a short half-life
decays faster than an atom
with a long half life

43. C-14 U-238 Time in 5730 year intervals
Can’t tell when an
individual atom will decay
BUT
50% of the atoms will decay
in one half life
Time in 4.5 billion year intervals
U-238
Time in 5730 year intervals
C-14

44. Applications of 1/2 life Radioactive Dating C-14
Used to date organic materials aged up to 60,000 years.

45. Radioactive Decay Formulas
Table N
1/2 lives of radioisotopes
Radioactive Decay Formulas 1 2
Number of
1/2 life periods
Fraction of
sample remaining =
Number of 1/2 life periods =
Time elapsed (t)
1/2 life (T)

46. Easier way than formula
100 = 1 whole
50 = 1/2
25 = ¼
12.5 = 1/8
6.25 = 1/16
3.125 = 1/32
= 1/64
1 half life
2 half life
Determine how many half life the element has gone through and divide by 2 that many times
3 half life
4 half life
5 half life
6 half life

47. The End