1. Nuclear Power Plant in Richland, WA
Nuclear Chemistry
Nuclear Power Plant in Richland, WA

3. Review From
Friday’s Lesson

4. The Band of Stability Certain isotopes are more stable than others
The ratio of protons to neutrons is important in determining stability
Example: Mg has 12 neutrons and 12 protons, U has 146 neutrons for 92 protons

5. Elements on the edge of
the band or outside of the
band are radioactive.
Radioactive isotopes
usually have more than
83 protons.

6. What holds the nucleus together?
Strong nuclear force (attractive)
Force pushing protons apart = repulsion due to positive charge (electrostatic force)
Protons: contribute to both the attractive force (strong force) and repelling force (charge)
Neutrons: contribute to the strong force (attractive) while having no charge. Act as the “glue” to bind the nucleus together

7. Binding Energy: Energy needed to hold the protons in the nucleus together (Also the energy released when an atom is split).

8. Mass and energy
During nuclear reactions, there is actually a small change in mass g
g g = +

9. Mass Defect: Measured mass of an atom is LESS THAN the sum of the masses of its particles.
E = mc2
Binding Energy
Mass
Speed of Light

10. How can we form a new element?
Must have a stable nucleus and exist long enough to be detected.
The neutron to proton ratio is an important factor in determining the stability of a nucleus.
Some isotopes are more stable than others. Unstable isotopes undergo nuclear decay to produce atoms with lower mass.

11. Nuclear Chemistry!
Nuclear chemistry: the study of the nucleus of the atom.
(so, it involves neutrons and protons, not electrons!)

12. Chemical vs. Nuclear Reactions
Chemical Reactions: # of atoms of each element remains unchanged
Example: 2H2 + O2  2H2O
Nuclear Reactions: Affect the nucleus of the atom—rearrangements of protons and neutrons.
**Sometimes the rearrangements lead to unstable or radioactive elements.

13. Radioactive Decay—Spontaneous breakdown of an atom which results in the emission of particles, energy or both.

18. Stability is relative
Some radioactive elements take thousands or millions of years to decay
Some radioactive elements take days, minutes, or fractions of a second to decay

19. Radioactive decay is measured in Half-lifes
Half-life: length of time it takes for half of a starting amount of an element to decay
Ex. Radium has a half-life of 1,620 years
How many years?
1620 years
100 Radium
atoms
1620 years
50 Radium atoms
25 Radium atoms
1620 years
1620 years
200 Radium
atoms
100 Radium
atoms
50 Radium
atoms
1620 years
25 Radium
atoms

20. Half-life cont.
A shorter half-life means an element is more radioactive because the radioactivity is released faster.
Ex. Which element is more radioactive?
Carbon-14 (half-life 5,720 years) or Radium-226 (half-life 1,620 years)?
Radium-226

21. Your turn!
You have a sample of 200 radioactive atoms and the half life is 20 years. After 100 years, how many atoms will be left? 100/20 = 5 half lives 200  100  50  25  12.5  6.25 atoms

22. Real World use of Half-Lives: Radioactive Dating
Ratio of carbon 12 to carbon 14 used to determine age of once-living things! (Carbon-14 has a half-life of 5,730 years)
Uranium-238 has a half-life of 4.5 billion years so is used to date rocks

25. Alpha (a) Radiation Beta (b) Radiation Gamma (g) radiation
3 types of Radiation
Alpha (a) Radiation
Beta (b) Radiation
Gamma (g) radiation

26. Types of Decay: The Particles4
1. Alpha positive charge 2
Same as a Helium nucleus
Alpha particle: two protons and two neutrons
Alpha particles are so large they cannot penetrate very far into matter (they can be shielded with a piece of paper!!)

27. Tho-Radia Face Cream
Promising instant curative and beautifying effects, Tho-Radia gained wide popularity in France during the early 1930's as a range of beauty products and perfumes. The face cream was especially popular and contained of 0.5g thorium chloride and 0.25mg radium bromide per 100g. It was even advertised as a creation of ‘Dr. Alfred Curie' although he was not a member of the Curie family and probably never existed.

28. Manufactured from 1918 to 1928 by the Bailey Radium Laboratories, Radithor was a well-known patent tonic that consisted of triple distilled water containing at a least one microcurie of Radium 226 and 228 isotopes. Said to cure stomach cancer and mental illness, it was even advertised as ‘Perpetual Sunshine' until it gained notoriety when Eben Byers, an American industrialist, drank a bottle a day for four year and consequently died in excruciating pain as cancer of the jaw caused his facial bones to disintegrate.
Radioactive Drinking Water
Ceramic jars that added radon to drinking water were popular during the early part of the 20th century. Revigator advertised itself as ‘nature's way to health' and its ores gave off millions of tiny rays of radiation that penetrated the water, creating ‘healthful radioactive water'.

29. Radioactive Toy Set
The Atomic Energy Lab first went on sale in 1951 and featured low levels of genuine radioactive material for children to experiment with. It remained on sale until the late 1970's and although the materials were labeled as ‘safe' you wouldn't find many parents today willing to let their kids play with uranium ore.

30. Radium Chocolate
Radium Chocolate manufactured by Burk & Braun was sold in Germany from 1931 to 1936, advertised for its powers of rejuvenation.

31. Types of Decay: The Particles
2. Beta negative charge -1
An electron is emitted and a neutron is converted into a proton!
beta particles =
high energy electrons
Beta particles also are a bit too large to penetrate you, and can be stopped with aluminum foil.

32. Types of Decay: The Particles
3. Gamma—high energy radiation
High energy electromagnetic radiation
No mass or charge
Often emitted along with beta or alpha radiation
Gamma rays penetrate, but can be stopped with lead (like x-rays!)

33. Alpha Decay
Atom releases an alpha particle.
Atomic # decreases becoming new element. +
Notice:
total starting mass equals total resulting mass: 238 =
total starting charge equals total resulting charge: 92 =
alpha particle
Conclusion: in alpha decay a nucleus splits into two smaller elements, one of which is always a helium nucleus

34. Balancing Nuclear Equations
Your turn!
Alpha Decay
210
206 Po Pb 4 + 2 84 82

35. Beta Decay
Atom releases a beta particle with zero mass & negative charge
Atomic number increases (becomes new element!) +
Notice:
total mass stays the same: 14 =
total charge stays the same: 6 = 7 - 1

36. Balancing Nuclear Equations
Beta Decay 27 27 Si P + 14 -1 15
An electron is emitted and a neutron is converted into a proton!

37. 217 221 Fr 4 α + At 2 85 87 234 234 Th β + Pa 90 91 -1 More Practice!
Francium-221 undergoes alpha decay. Write the nuclear reaction below.
217
221 Fr 4 α + At 2 85 87
Thorium-234 emits a beta particle. Write the nuclear reaction below.
234
234 Th β + Pa 90 91 -1

38. The road to stability may be long!
Things to notice:
There are multiple steps
some steps are alpha decay, some are beta decay
the stable end point is an element with atomic # less than 83 (lead)
there are also unstable lead isotopes which are intermediates

39. STOP DAY 1

40. What are some uses for radioactive elements??
Atomic Weapons
Nuclear Medicine
Nuclear Power

41. Radiation Therapy
Used to treat cancer (but yes, too much radiation can actually CAUSE cancer)
Mechanism: Radiation beams knock off electrons from atoms making up DNA chains and turn them into free radicals (damaging them!)
Polonium, Cobalt, Cesium & Radium are all elements used in radiation therapy.

42. Nuclear Power
Fission—Splitting of a heavy nuclei (like Uranium) **Radioactive products
Fusion—Combining of 2 or more light nuclei (H + H  He) **Non-radioactive products. **Requires extremely high temperatures (sun/stars)
Both release LARGE amounts of ENERGY!

43. Fission Splitting one nucleus into smaller fragments
Nuclear power plants and most nuclear weapons rely on nuclear fission

44. What is a Chain Reaction?
Chain Reaction: A reaction in which the material that starts the reaction is also one of the products and can start another reaction.

45. Fusion Two nuclei combine
Release large amounts of energy, but requires very high temperatures
At such high temperatures, nuclei are moving so fast that collisions between them can overcome the natural repulsion of their positive charges.
Examples
The Sun
The Hydrogen bomb

47. How does a Nuclear Power
Plant Work?

48. Review: Splitting Atoms Releases Neutrons, Making Heat
The splittingor fissioningof the atoms then releases neutrons, along with energy in the form of heat.

49. Heat Produces Steam, Generating Electricity
Turbine
Generator
Steam produced
Electricity
This process continues in a chain reaction, producing a great deal of heat. It is this process—creating heat through the splitting of atoms—that turns water to steam. The steam is moved from the reactor to turn the turbine-generator, which makes electricity. All radioactive water stays within the reactor system and is not released into the environment.
Heat

50. ATOMIC WEAPONS

51. What are they?
Nuclear weapons derive their destructive force from nuclear fusion or fission.

52. How many have there been? Where were these weapons dropped?
Two nuclear weapons have been detonated—both by the United States at the end of World War II.
Where were these weapons dropped?

53. Hiroshima Nagasaki August 6th, 1945 Uranium
140,000 people killed (instantly,
or from illness associated with radiation)
Nagasaki
August 9th, 1945
Plutonium
80,000 people killed (instantly, or from illness associated with radiation)

54. Manhattan Project
( )
The project to develop the first nuclear weapon during WWII (U.S., Canada & the U.K.)
Robert Oppenheimer: Scientific researcher (Father of the Atomic Bomb)
1945—Trinity Test (First detonation of a nuclear bomb) in New Mexico

55. 2 Main Types of Nuclear Weapons:
#1: Nuclear Fission—(Atomic Bombs)

56. 2 Main Types of Nuclear Weapons:
#2: Nuclear Fusion—(Hydrogen Bombs)
Use the energy of a fission bomb to heat the fusion fuel
Over 1,000 times more powerful than a fission bomb!
Only 6 countries have detonated one: U.S., Russia, U.K., China, France, and India

57. Nuclear Fallout—What is it?
Nuclear fallout: the residual radiation hazard from a nuclear explosion, so named because it "falls out" of the atmosphere into which it is spread during the explosion.

58. Hotter stars will produce larger elements
“Big Bang” = H & He
Cooler Stars = fuse H atoms into He
Bigger/Hotter stars = slightly heavier elements made, up to Fe
Supernova (explosion of star) = create heaviest elements (up to U)
Video clip: minutes 55:30 to 58

59. Nucleosynthesis: forming new elements
Some light to medium-sized elements formed by simple fusion of two elements
Elements heavier than iron are believed to be made by neutron capture. This is a two-step process
Neutron collides and fuses with the nucleus of an atom
When the nucleus is overloaded with these neutrons, it will undergo beta decay (a neutron will turn into a proton) +
Note: to find the product of a fusion reaction,
Add up the mass #’s and atomic #’s of your starting elements
Example from p92 in book
Step 1: Fusion with neutrons + +
Step 2: beta decay, creation of proton +