Download Nuclear Chemistry 9

Nuclear Chemistry
Objective: 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 
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Radioactivity video – 4 minutes
http://ed.ted.com/lessons/radioactivity-expect-theunexpected-steve-weatherall
Review questions:
http://ed.ted.com/lessons/radioactivity-expect-theunexpected-steve-weatherall#review
Dig deeper:
http://ed.ted.com/lessons/radioactivity-expect-theunexpected-steve-weatherall#digdeeper
Review: Radioactive Isotopes
A radioactive isotope has an unstable nucleus
that undergoes spontaneous changes.
- Emits particles
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-
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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
Next slide
Charge Mass Rad.Strength
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
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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.
2.
3.
4.
27
4 He ---> 30 P + ?
Al
+
13
2
15
238 U  234 Th + ?
92
90
14 C  0 e + ?
6
-1
239 Pu + 4 He  242 Cm + ?
94
2
96
Nuclear Equations Practice Website
Nuclear Reactions
Emission of Alpha or Beta particles
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http://phet.colorado.edu/en/simulation/betadecay
http://phet.colorado.edu/en/simulation/alphadecay
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
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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
Elapsed time
Half-Lives
0
0
Amount
remaining
100 g
1
1.5 year
50 g
2
3 years
25 g
3
4.5 years
12.5 g
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Examples of the Half Life of Radioactive Elements
Tearing Through a Half Life
800 Billion Bismuth-210 Atoms
Time (years)
Half Life:
http://phet.colorado.edu/en/simulation/radioac
tive-dating-game
Number of radioactive isotopes
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Number of years
Fission and Fusion
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http://phet.colorado.edu/en/simulation/nuclear
-fission