Nuclear Chemistry
Forms of Energy • The five main forms of energy are: – Heat – Chemical – Electromagnetic – Nuclear – Mechanical
Nuclear Radiation Many elements can change through radioactivity. -Radioactive elements have unstable nuclei. -Radioactive elements can decay. – Emit radiation – Can become a different isotope of the same element – Can become a different element!
Types of Radiation • Alpha Particle – Helium nucleus with a + 2 charge – The largest radioactive particle – Don’t penetrate very deep
• Beta Particle – A fast moving electron -1 charge – Can travel through paper, but wood or aluminum will stop it.
• Gamma Particle – Tiny and too small to measure (like photons) – No charge – Travel through clothes and even walls
www.geology.fau.edu/course_info/fall02/ EVR3019/Nuclear_Waste.ppt
Alpha decay Alpha particle has a mass of 4. -- 2 protons and 2 neutrons --Mass goes down by 4 --Atomic # goes down by 2
7
Beta decay Beta particle has a tiny mass. -- A neutron is converted to a proton --Mass stays the same --Atomic # goes up by 1 234Th 90
234Pa
+ e-1
91
beta particle 8
Gamma radiation No change in atomic or mass number 11B 5
11B 5
+
0
0
boron atom in a high-energy state
9
Comparison of Chemical and Nuclear Reactions Chemical Reactions Occur when bonds are broken or formed Involve only valence electrons Associated with small energy changes
Nuclear Reactions Occur when nuclei combine, split, & emit radiation Can involve protons, neutrons, & electrons Associated with large energy changes
Atoms keeps same identity Atoms of one element are although they may gain, often converted into atoms lose, or share electrons, of another element and form new substances Temperature, pressure, concentration, and catalysts affect reaction rates
Temperature, pressure, and catalysts do not normally affect reaction rates
Radiation
Composition & Symbol
Is shielded or stopped by?
Alpha
2 p+ and 2 n0
paper
Beta
Stream of high speed e-
Clothing, wood
Gamma
Very high energy Concrete, lead electromagnetic radiation
Nuclear Fission
• A heavy nucleus splits into more stable nuclei of intermediate mass.
Little Boy and Fat Man
Atomic Bombs • Atomic bombs are an example of Fission Reactions. • “Little boy” and “Fat man” were Atomic bombs made from fission reactions with uranium and plutonium respectively. • A fission chain reaction is started and continues until the bomb destroys itself.
Nuclear Fusion • Low-mass nuclei combine to form a heavier, more stable nucleus.
Hydrogen Bombs • Hydrogen bombs are an example of nuclear fusion. • Two isotopes of hydrogen, 2H and 3H, fuse together and produce a lot of energy in the process. • H-bombs release significantly more energy than atomic bombs.
The Sun: Nuclear Fusion Sun
+
+
2 e Two beta particles (electrons)
4 2
Four hydrogen nuclei (protons)
1 0 -
1 1
4H
He +
One helium nucleus
Energy
Comparing Fission and Fusion
http://media-1.web.britannica.com/eb-media/03/72203-035-4D92BDBC.jpg
Nuclear Fission
Nuclear Fusion
Nuclear Fission
A heavy atom splits into two or more lighter nuclei
Ex: Atomic Bombs & Nuclear reactors
Nuclear Fusion
Release huge amounts of energy
Produce nuclear waste
High temp and pressure are used to combine light atoms to make heavier atoms
Ex: Fuels the sun and stars & Hydrogen Bombs
Nuclear Power Plants
map: Nuclear Energy Institute
Nuclear Power Plants • Uranium-235 undergoes nuclear fission and releases thermal (heat) energy. • This turns water to steam which spins turbines. • The turbines produce electrical energy. • Nuclear waste is fuel rods with unreacted uranium and radioactive products of fission. Right now this waste is buried in waste management facilities, like Yucca Mountain.
Did You Know ?
http://www.ambrosevideo.com/resources/documents/89.jpg
http://images4.wikia.nocookie.net/__cb20060611033960/schools/images/0/0b/Chart.JPG
Half-Life • The time needed for one-half of the nuclei in a radioisotope to decay and emit their radiation to form a different isotope • • Uranium 235 • Plutonium 239
Half-time 710 million yrs 24.000 yrs
emitted alpha, gamma alpha, gamma
• During operation, nuclear power plants produce radioactive wastes, including some that remain dangerous for tens of thousands of years
www.bio.miami.edu/beck/esc101/Chapter14&15.ppt
Relative Doses from Radiation Sources
cstl-cst.semo.edu/bornstein/BS105/ Energy%20Use%20-%203.ppt
Effects of Radiation • Genetic damages: from mutations that alter genes • Genetic defects can become apparent in the next generation • Cellular damages: to tissue, such as burns, miscarriages & cancers
www.bio.miami.edu/beck/esc101/Chapter14&15.ppt
