1. Chapter 22 notes

2. Types of nuclear reactions
Fission- splitting of nucleus- nuclear waste
Fusion- nuclei can fuse together-no nuclear waste, but need 100 million degrees C to make reaction happen

3. Nuclear vs. Chemical reactions
Part of atom involved?
Valence e-
Protons and neutrons
How reaction is started?
Atoms in close proximity with high temp, pressure, catalysts, or concentrations of reactants
High temperature or bombard with high-speed particles
Outcome of rxn
Ionic or covalent bonds
# protons or neutrons changes
Amt of energy released or absorbed
Small
Huge
Examples
Digestion, making medicines, cleaning products
Nuclear energy, X-rays, cancer treatment, the sun

4. Forces in nucleus
Strong nuclear forces overcomes repelling force of protons to keep nucleus together
This force attracts every proton and neutron to each other (stronger than electromagnetic repelling force)
To keep nucleus together in heavier atoms, need more neutrons than protons to overcome repelling force
However past 83 p= strong nuclear force is not enough to keep atom together- unstable

5. Radioactivity Nucleus emits particles or energy
Ex- U-238 decays eventually to Pb-206 (5-billion year process)
3 types of radioactive decay
Alpha- helium atom released from unstable nucleus (2p and 2n)
Beta- neutron splits into a proton and electron
Gamma- release of high energy, radiation from nucleus (shorter wavelength than X-rays)

6. Nuclear power
Sun power is nuclear power (heat generated from fusion reactions)
Nuclear reactors- use fission to produce steam to run turbines that generate electricity

7. Nuclear waste
Whereas coal and fossil fuel burning contributes to global warming, nuclear reactors produce nuclear waste
Waste is decaying nuclear atoms which give off radiation as they decay
½ time it takes a sample of a radioactive element to decay halfway
Most radioactive elements have long ½ lives
Nuclear reactors- use uranium- long ½ life

8. Nuclear Waste/reactors continued
How is the waste stored? Controversial issue!
Right now stored in containers meant to last 100years
Proposal is to store in Yucca Mtn, Nevada
US- 20% energy from nuclear fission- France 75%- Sweden and Belgium 50% or more

9. Nuclear reactions in science
Use radioactive isotopes for medical tests
Use radioactive isotopes to trace underground water supplies
Nuclear reactions used to sterilize packaged foods
Can predict age of fossils using radioactive isotopes
Marie Curie- what were her contributions

10. Protection against radiation
Alpha particles- blocked by a sheet of paper
Beta particles- clothing or wood
Gamma- most dangerous need lead or concrete to block these