1. NUCLEAR CHEMISTRY

2. DIFFERENTIATE BETWEEN FISSION AND FUSION.
DESCRIBE THE NUCLEAR COMPOSITION OF UNSTABLE ISOTOPES AND THE RESULTING CHANGES TO THE THEIR NUCLEAR COMPOSITION.
IDENTIFY TYPES OF NUCLEAR EMISSION, INCLUDING ALPHA PARTICLES, BETA PARTICLES, AND GAMMA RADIATION
DIFFERENTIATE BETWEEN FISSION AND FUSION.
IDENTIFY USES AND POSSIBLE NEGATIVE SIDE EFFECTS OF NUCLEAR TECHNOLOGY.
COS 11.0, 11.1, 11.2, 11.3

3. WHAT YOU’LL LEARN
Identify three types of nuclear radiation and their properties.
Distinguish between fission and fusion, and provide examples of each.
List and explain three beneficial uses and three possible risks of nuclear radiation.
Contrast properties of radioactive and stable nuclei.

4. FYI: Historical Perspective
Henri Becquerel
Discovers natural radioactivity

5. The discovery of radiation
In 1896 Henri Becquerel made an important discovery.
He accidentally had placed a piece of uranium ore on top of an unexposed photographic plate. Later, when the plate was developed, the image of the rock was found on the plate.
Based on further experiments, he concluded that the plate had been exposed by rays given off by the uranium.

6. Madame Curie discovers Radium and Polonium
Following Becquerel’s discovery, Marie Sklodowska Curie and her husband, Pierre Curie, attempted to isolate the “radioactive” material from the uranium ore.
In doing so they discovered two new elements, Radium and Polonium, both of which were more radioactive than the original ore.

7. Ernest Rutherford
Rutherford investigated this new property of matter and discovered that, in the process of emitting radiation, atoms of one element became atoms of another element.
Today, we describe the process of an atom of one element becoming an atom of a different element as transmutation.

8. Rutherford discovered the different types of radiation
Rutherford was the first to identify and name two different types of radiation given off when an atom of one element underwent transmutation and became an atom of another element. The two types of radiation he found were:
The alpha particle (a)
The beta particle (b)
A third type of radiation that was discovered later is called:
Gamma radiation (g)

9. Nuclear Reactions Involve changes in the composition of nuclei
Accompanied by the release of tremendous amounts of energy
Where does this energy come from?

10. Mass Defect Some of the mass can be converted into energy
Shown by a very famous equation!
E=mc2
Energy
Mass
Speed of light

11. Nuclear Fission
The splitting of a heavy nucleus into lighter nuclei

12. Nuclear Fusion
The combination of light nuclei to produce a heavier nucleus

13. Nuclear Radiation Chapter 9 Radioactivity:
process by which an unstable nucleus emits one or more particles or energy in form of electromagnetic radiation.
nuclear radiation:
particles that are released from nucleus during radioactive decay.
What makes the nucleus unstable?

14. The neutron-to-proton ratio determines the stability of the nucleus
For low atomic #’s:
Equal #’s of protons and neutrons
Above atomic #20:
More neutrons than protons
Note: this stability has nothing to do with electrons and valence shells (we’re talking about nucleons)

15. Nuclides Different atomic forms of all elements (isotopes)
Most small nuclides have equal # of protons and neutrons
Some nuclides have “magic #’s” of protons and neutrons and are especially stable

16. Nuclei whose neutron-to-proton ratio is unstable undergo radioactive decay by emitting 1 or more particles and/or electromagnetic rays:

17. Type/ symbol Identity Mass (amu) Charge Penetration Alpha Beta Gamma
Nuclei whose neutron-to-proton ratio is unstable undergo radioactive decay by emitting 1 or more particles and/or electromagnetic rays:
Type/
symbol
Identity
Mass (amu)
Charge
Penetration
Alpha
Beta
Gamma
Proton
Neutron
helium nucleus
4.0026 2+
low
electron 1-
low-med
high energy radiation
high
proton, H nucleus
1.0073 1+
low-med
neutron
1.0087
very high

18. Nuclear Reactions vs. Normal Chemical Changes
Nuclear reactions involve the nucleus
The nucleus opens, and protons and neutrons are rearranged
The opening of the nucleus releases a tremendous amount of energy that holds the nucleus together – called binding energy
“Normal” Chemical Reactions involve electrons, not protons and neutrons

19. Types of Radiation
Alpha (ά) – a positively charged helium isotope - we usually ignore the charge because it involves electrons, not protons and neutrons
Beta (β) – an electron Gamma (γ) – pure energy; called a ray rather than a particle

20. Penetrating Ability
Can be stopped by a sheet of paper

21. Balancing Nuclear Reactions
In the reactants (starting materials – on the left side of an equation) and products (final products – on the right side of an equation)
Atomic numbers must balance
and
Mass numbers must balance
Use a particle or isotope to fill in the missing protons and neutrons

22. ALPHA PARTICLES consists of two protons and two neutrons
Composed of He nucleus atom w/ +2 charge
Least penetrating type of radiation
Can be stopped by a sheet of paper

24. BETA PARTICLES
negatively charged electron emitted during certain types of radioactive decay
Emitted at high speeds from nucleus

25. Beta decay

26. GAMMA PARTICLES gamma ray
high-energy photon emitted by a nucleus during fission and radioactive decay
Most penetrating type of radiation
Does not have a charge nor mass

27. NEUTRON EMISSION
consists of matter that is emitted from an unstable nucleus.
Neutrons are able to travel farther through matter than either alpha or beta particles.

28. Nuclear Fission
process by which a nucleus splits into two or more fragments and releases neutrons and energy.
Produces nuclei of lower mass than reactants
Used to produce nuclear power (electricity)
Produces extremely toxic waste

29. Nuclear Fusion
process in which light nuclei combine at extremely high temperature, forming heavier, more stable nuclei and releasing energy.
Produces nuclei of higher mass than reactants
Takes place in sun.
Helium major by product

30. Beneficial Uses of Nuclear Radiation
Smoke detectors
small alpha-emitting isotope detects smoke particles in air.
radioactive tracer:
radioactive material that is added to a substance so that its distribution can be detected later.
understand biochemical processes in plants.
Radiotherapy:
treatment that uses controlled doses of nuclear radiation for treating diseases such as cancer.

31. Nuclear Medicine: Imaging
Thyroid imaging using Tc-99m

32. Food Irradiation
Food can be irradiated with g rays from 60Co or 137Cs.
Irradiated milk has a shelf life of 3 mo. without refrigeration.
USDA has approved irradiation of meats and eggs.

33. Possible Risks of Nuclear Radiation
Ionization
change in number of electrons in an atom or molecule, causing the particle to be positively or negatively charged.
Radiation sickness
results from high levels of nuclear radiation.
Dosimeter
device that measures the amount of nuclear radiation exposure.
Studies have shown a relationship between exposure to high levels of nuclear radiation and cancer.

34. Possible Risks of Nuclear Radiation
Radon gas:
colorless and odorless,
produced by the decay of uranium-238
naturally occurs in soil and rock.
Causes lung cancer