themes: stability and change conservation of energy and matter
TRANSCRIPT
Themes:Stability and Change
Conservation of Energy and Matter
What types of isotopes are unstable?
Unstable isotopes have larger differences between number of protons and neutrons.
Look at your periodic table…what happens as the atomic # gets higher?
When a radioactive nucleus spontaneously decomposes.
In a nuclear equation both the atomic number and the mass number must be conserved.
How is that shown below??
The types of nuclear reactions we will go over are as follows.
The examples are on the powerpoint for your review, but we will do examples on the board in class: Alpha Beta Gamma Positron Emission Electron capture Nuclear bombardment
Alpha Produces
Helium Nucleus
Atomic Mass:Decrease by 4
Atomic #:Decrease by 2
Beta Produces
An electron
Atomic mass:Same
Atomic#: increase by 1
Gamma Produces
EnergyUsually accompanies another type of decay
Atomic mass and atomic number remain the same.
Positron Produces
Like a positron with a + charge
Atomic Mass:Same
Atomic #:Decrease by 1
Electron Capture
Inner electrons are captured by the nucleus.
Atomic Mass:SameAtomic number:Decrease by 1
Nuclear Bombardment
A particle is shot into the nucleus:Eg. Alpha particle or a neutron
See Example below:
Mass: Will increase
Atomic #: Will usually change
Geiger Counter—Radiation produces ionizing energy that knocks off electrons from argon. This causes an electric current which is detected.
Fiesta Ware Demonstration on youtube.http://www.youtube.com/watch?v=FKn9zJuyfWQ
Type Penetration Damaging Effects
Alpha Blocked by skin Ionizing substances in the body causing damage
Beta Penetrates 1 inch into skin, can be blocked by Aluminum foil
Least damaging
Gamma Deep penetration. Blocked by lead
Damaging because this is a very high energy form of electromagnetic radiation. Eg. Most commonly used to kill cancer cells
Positive Uses Detection on imaging machines “Killing” cells in tumors that can’t be
Negative Affects High exposure—damaging to cells (eg.
Hiroshima) Long term low exposure—
Mutation to DNA leading to cancer Mutation to DNA in eggs/sperm
Time required for half of the original same of nuclei to decay.
Carbon-14 half-life 5730 years
Uranium-238 half-life 4.5 billion years
Iodine-131 half-life 8.1 days
What type of function is this?
Use howstuffworks.com to investigate nuclear fission and fusion.
Create a Venn Diagram in your notes to compare and contrast the two processes
Case study will identify the use of isotopes in medicine.
Model will use pennies to represent radioactive decay.
Practice graphing and lab notebook skills!