Nuclear ChemistryObjective: To explain the process of radioactive decay using nuclear equations and half life
Essential Question: How do unstable (radioactive) isotopes become stable?
Review: Radioactivity introduction - Radioactivity video – 4 minutes http://ed.ted.com/lessons/radioactivity-expect-the-unexp
ected-steve-weatherall Review questions: http://ed.ted.com/lessons/radioactivity-expect-the-unexp
ected-steve-weatherall#review Dig deeper: http://ed.ted.com/lessons/radioactivity-expect-the-unexp
ected-steve-weatherall#digdeeper
Review: Radioactive IsotopesA radioactive isotope has an unstable nucleus
that undergoes spontaneous changes. - Emits particles
- 1.- 2.
- Emits energy in the form of __________ waves.
- Transmutates into another element
Types of Radiation
Alpha Decay
Beta decay
Gamma Decay
Particles emitted from a radioactive isotope
Type Symbol Charge Mass Rad.Strength
Next slide
Radiation Strength: Explain in your notes how each of the radioactive emissions are blocked.Which is the most damaging (strongest)?
Strong Nuclear Force:Holds the nucleus together
Limit to the # neutrons: A nucleus with too many neutrons will be unstable and change
Balancing Nuclear Reactions
Keep track of atomic number (Z) and mass number (A): protons & neutrons
Totals of A & Z must be the same before and after the reaction.
Shown by “Before” “ After”
Nuclear reactions
Total number of atomic numbers and the total mass numbers must be equal on both sides of the equation.
Examples:
Nuclear Equations
1. 2713Al + 4
2He ---> 3015P + ?
2. 23892U 234
90Th + ?
3. 146C 0
-1e + ?
4. 23994Pu + 4
2He 24296Cm + ?
Nuclear Equations Practice Website
Nuclear Reactions Emission of Alpha or Beta
particles http://phet.colorado.edu/en/simulation/beta-decay
http://phet.colorado.edu/en/simulation/alpha-decay
Radioactive decay
No two radioactive isotopes decay at the same rate. Therefore, decay rate can be used to identify the isotope. Decay is measured by half life.
Half-life
Measure of Radioactive decay rate. Measured as the time it takes for ½ of a
sample of radioisotope’s nuclei to decay into its products.
Half Life
Decay of a radioisotope
Number of Half-Lives
Elapsed time Amount remaining
0 0 100 g
1 1.5 year 50 g
2 3 years 25 g
3 4.5 years 12.5 g
Examples of the Half Life of Radioactive Elements
Tearing Through a Half Life800 Billion Bismuth-210 Atoms
Time (years)
Half Life:
http://phet.colorado.edu/en/simulation/radioactive-dating-game
Number of years
Num
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of r
adio
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otop
es
Fission and Fusion
http://phet.colorado.edu/en/simulation/nuclear-fission
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