Why are some elements
(isotopes) more stable than
others?
The
Nucleus
The
Electric
Force
Protons hate Protons
Strong Force Facts
• Neutrons act like cement
• Strong Force is very strong over a small
distance (about the distance of two protons)
• Small elements, 1 proton to 1 neutron will do
Large Elements
http://www.ptable.com/
Beta Particle
Thorium
Protactinium
(Th) (Pa)
Alpha Particle
Protactinium
Actinium
(Ac)(Pa)
Beta
Gamma
& Alpha
Radiation
Radiation
Quick Quiz
• What is the difference between the electric
force and the strong force?
• What are the three types of radiation that are
present in radioactive decay?
Example Uranium 238
How can radioactive decay be useful?
Dating
• The time it takes for half of the original quantity to decay
• The half-life of an element is constant, and not affected
by external conditions
Iodine-131
decays to Xenon-131
32
40
Day: 116
824
Half-life: 8 days
Number of
02
8
Iodine: 4116
16
12
814
0
Xenon: 15
Radiometric Dating
(isotopic dating)
Organic:
• Radiocarbon dating
• Range: 50,000 years
• Carbon in atmosphere not
constant
Inorganic:
• Uranium to Lead dating
• Range: 7 million to 4.5
billion years
Quick Quiz 2
• What is half-life?
• Is radiocarbon dating extremely accurate, why
or why not?
Radiation is dangerous!
How do they measure radiation!
Rad
• a unit of absorbed
radiation dose
• 1 rad = 10 mj
Rem
• amount of biological
damage due to radiation
dose
• 1000 rem or higher will
be fatal
Geiger counter
Table of rad vs rem
Radiaton
rad
rem
Gamma
1
1
X-Ray
1
1
Beta particle
1
1
Alpha particle
1
20