1. Nuclear

2. Band of Stability n = p Number of neutrons Number of protons 160 150
140
130
120
110
100 90 80 70 60 50 40 30 20 10
Band of Stability
n = p
Number of neutrons
The band of black squares, which shows the stable nuclides, is known as the band of stability. In general, the further a nuclide is from the band of stability, the shorter the half-life of the nuclide.
No stable isotopes are known for elements with atomic numbers higher than 83 (bismuth).
Stable nuclides
Naturally occurring radioactive nuclides
Other known nuclides
Number of protons

3. Nuclear Decay Why nuclides decay… b a
need stable ratio of neutrons to protons
120
100 80 60 40 20
Neutrons (A-Z)
Protons (Z)
P = N b
stable
nuclei a
e-capture or
e+ emission
Courtesy Christy Johannesson
DECAY SERIES TRANSPARENCY

4. Nuclear Decay Why nuclides decay… b a
need stable ratio of neutrons to protons
stable
nuclei
P = N b
stable
nuclei a
P = N
120
120
e-capture or
e+ emission
100
100 80 80 60 60
Neutrons (A-Z)
Neutrons (A-Z) 40 40 20 20 20 40 60 80
100
120 20 40 60 80
100
120
Protons (Z)
Protons (Z)

5. Discovery of the Neutron+ +
Chadwick is credited with the discovery of the neutron
as a result of this transmutation experiment.
James Chadwick bombarded beryllium-9 with alpha particles,
carbon-12 atoms were formed, and neutrons were emitted.
Dorin, Demmin, Gabel, Chemistry The Study of Matter 3rd Edition, page 764

6. Types of Radiation Type Symbol Charge Mass (amu) Alpha particle 2+
Beta particle 1-
Positron 1+
Gamma ray

7. Alpha, Beta, Gamma Rays b rays g rays a rays Lead block (+) (-)
(negative charge)
Aligning
slot
(no charge)
g rays
a rays
Radioactive
substance
(positive charge)
Photographic
plate
Electrically charged
plates
(detecting screen)

9. Alpha, Beta, Positron Emission
Examples of Nuclear Decay Processes
a emission
(alpha)
b- emission
(beta)
b+ emission
(positron)
Although beta emission involves electrons, those electrons come from the nucleus. Within the nucleus,
a neutron decays into a proton and an electron. The electron is emitted, leaving behind a proton to
replace the neutron, thus transforming the element. (A neutrino is also produced and emitted in the process.)
Herron, Frank, Sarquis, Sarquis, Schrader, Kulka, Chemistry, Heath Publishing,1996, page 275

10. Nuclear Decay Numbers must balance!! Alpha Emission parent nuclide
daughter
nuclide
alpha
particle
Numbers must balance!!
Courtesy Christy Johannesson

11. Nuclear Decay Beta Emission electron Positron Emission positron
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12. Nuclear Decay Electron Capture electron Gamma Emission Transmutation
Usually follows other types of decay.
Transmutation
One element becomes another.
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13. Half-Lives of Isotopes
Half-Lives and Radiation of Some Naturally Occurring Radioisotopes
Isotope Half-Live Radiation emitted
Carbon-14
5.73 x 103 years b
Potassium-40
1.25 x 109 years
b, g
Radon-222
3.8 days a
Radium-226
1.6 x 103 years
a, g
Thorium-230
7.54 x 104 years
a, g
Thorium-234
24.1 days
b, g
Uranium-235
7.0 x 108 years
a, g
Uranium-238
4.46 x 109 years a

14. Half-Life Plot Half-life of iodine-131 is 8 days20
Half-life of iodine-131 is 8 days 15
1 half-life
Amount of odine-131 (g) 10 16
2 half-lives 5 24
3 half-lives 32
4 half-lives
etc… 40 48 56 8
Time (days)
Timberlake, Chemistry 7th Edition, page 104

15. Half-Life Half-life (t½)
Time required for half the atoms of a radioactive nuclide to decay.
Shorter half-life = less stable.
1/1
Newly formed
rock
Potassium
Argon
Calcium
Ratio of Remaining Potassium-40 Atoms
to Original Potassium-40 Atoms
1/2
1/4
1/8
1/16
1 half-life
1.3
1 half-lives
2.6
3 half-lives
3.9
1 half-lives
5.2
Time (billions of years)

16. Half-Life Half-life (t½)
Time required for half the atoms of a radioactive nuclide to decay.
Shorter half-life = less stable.
1/1
1/2
1/4
1/8
1/16
Ratio of Remaining Potassium-40 Atoms
to Original Potassium-40 Atoms
1 half-life
1.3
1 half-lives
2.6
3 half-lives
3.9
5.2
Time (billions of years)
Newly formed
rock
Potassium
Argon
Calcium

17. Nuclear Fusion + + + Sun Energy Four hydrogen nuclei (protons)
Two beta
particles
(electrons)
One
helium
nucleus

18. Conservation of Mass …mass is converted into energy
Hydrogen (H2) H = amu
Helium (He) He = amu
FUSION
2 H  He ENERGY
1.008 amu
x 4
amu = amu amu
This relationship was discovered by Albert Einstein
E = mc2
Energy= (mass) (speed of light)2

19. Mass Defect
Difference between the mass of an atom and the mass of its individual particles.
amu
amu
Courtesy Christy Johannesson

20. The Energy of Fusion
The fusion reaction releases an enormous amount of energy relative to the
mass of the nuclei that are joined in the reaction. Such an enormous amount
of energy is released because some of the mass of the original nuclei is con-
verted to energy. The amount of energy that is released by this conversion
can be calculated using Einstein's relativity equation E = mc2.
Suppose that, at some point in the future, controlled nuclear fusion becomes
possible. You are a scientist experimenting with fusion and you want to
determine the energy yield in joules produced by the fusion of one mole of
deuterium (H-2) with one mole of tritium (H-3), as shown in the following
equation:

21. amu
amu
amu
amu
amu
amu
amu
amu
First, you must calculate the mass that is "lost" in the fusion reaction. The
atomic masses of the reactants and products are as follows:
deuterium ( amu), tritium ( amu), helium-4 ( amu),
and a neutron ( amu).
Mass defect: -
amu