Title: 4.4%20Radioactivity
14.4 Radioactivity
2Nuclear Reaction - involves change in nucleus
- Radioactivity substances spontaneously emit
radiation. - Element can change into another element.
- Occurs because nucleus becomes unstable.
- Unstable atoms gain stability by losing energy.
- Energy lost by emitting radiation.
- Chemical Reaction change of 1 or more substances
into new substances. - atoms are rearranged
- nucleus is unchanged
3 Nuclear vs. Chemical Reactions
Atoms are rearranged
4Types of Radiation
Type Symbol Mass Charge Nature Penetra- tion
Alpha 4 2He 4 2 Helium Nucleus Sheet of Paper
Beta ß 0 -1e 0 1/1840 -1 From nucleus High speed electrons Aluminum Foil
Gamma 0 0? 0 0 Electro- Magnetic Radiation Lead Shielding
5Penetration of Radiation
6Nuclear Equations Mass numbers atomic numbers
must be conserved.
- Alpha emission
- 226Ra ? 222Rn 4He
- 88 86 2
- alpha particle
- Mass and Atomic Conserved
- 226 ? 222 4
- 88 ? 86 2
7Beta Emission Ex. Carbon-14 decays to produce a
beta particle.
8Gamma Emission accounts for most of energy lost
during radioactive decay.
- Usually accompanies alpha beta.
- 238U ? 234Th 4He 0?
- 92 90 2 0
9Nuclear stability primarily determined by
- Ratio of neutrons to protons.
- Size of nucleus.
- Atoms with atomic greater than 83 (Bismuth) are
unstable. - Atoms eventually decay to form stable,
nonradioactive atoms.
10Radioactive Decay Series
11Nuclear Fission (Splitting)
- Unstable atoms break apart into smaller ones.
- Releases tremendous amounts of energy.
- Nuclear power plants (U-235)
12Nuclear Fusion (Uniting)
- Fusing together smaller elements to make larger
ones. - Produces all elements larger than He
- Fusion releases tremendous amounts
of energy. (Greater than fission) - Occurs on the Sun (and stars)
- Cleaner method but no current
technology for power plants.
13Nuclear Energy (Fission)Pros Cons
- Does not cause air pollution
- (no CO2 emissions, etc.)
- Doesnt use up
- fossil fuel (coal)
- Less global warming, acid rain
- Limited amount of nuclear fuel (Ex. U-235)
- Spent fuel is radioactive
- Transportation storage problems!
- Water used in cooling process may cause problems
when released to environment.
14 Coal vs. Nuclear Power
15 Pro Con
- Coal waste has more radiation than spent fuel!
- Except for Chernobyl, minimal releases of
radiation.
- High cost of nuclear power (due to government
regulations).
1615 power by nuclear52 by coal power
17The End
- Chain Reaction Neutrons released start
- new reactions