nuclear chemistry. forms of energy the five main forms of energy are: – heat – chemical –...
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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
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Alpha decay
Alpha particle has a mass of 4. -- 2 protons and 2 neutrons--Mass goes down by 4--Atomic # goes down by 2
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Beta decay
234Th ® 234Pa + e-1
90 91
beta particle
Beta particle has a tiny mass. -- A neutron is converted to a proton--Mass stays the same--Atomic # goes up by 1
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Gamma radiation
No change in atomic or mass number
11B 11B + 0 5 5 0
boron atom in a high-energy state
Chemical Reactions Nuclear Reactions
Occur when bonds are broken or formed
Occur when nuclei combine, split, & emit radiation
Involve only valence electrons
Can involve protons, neutrons, & electrons
Associated with small energy changes
Associated with large energy changes
Atoms keeps same identity although they may gain, lose, or share electrons, and form new substances
Atoms of one element are often converted into atoms of another element
Temperature, pressure, concentration, and catalysts affect reaction rates
Temperature, pressure, and catalysts do not normally affect reaction rates
Comparison of Chemical and Nuclear Reactions
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 electromagnetic radiation
Concrete, lead
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
+ +
Fourhydrogen
nuclei(protons)
Two betaparticles
(electrons)
Oneheliumnucleus
He e2 H4 4
2
0
1-
1
1 + Energy
Comparing Fission and Fusion
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Nuclear Fission Nuclear Fusion
Nuclear Fission Nuclear Fusion
A heavy atom splits into two or more lighter nuclei
Ex: Atomic Bombs & Nuclear reactors
High temp and pressure are used to combine light atoms to make heavier atoms
Ex: Fuels the sun and stars & Hydrogen Bombs
Release huge
amounts of energy
Produce nuclear waste
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.
Did You Know ?
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• The time needed for one-half of the nuclei in a radioisotope to decay and emit their radiation to form a different isotope
• Half-time emitted • Uranium 235 710 million yrs alpha, gamma• Plutonium 239 24.000 yrs alpha, gamma
• During operation, nuclear power plants produce radioactive wastes, including some that remain dangerous for tens of thousands of years
Half-Life
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
• 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
Effects of Radiation
www.bio.miami.edu/beck/esc101/Chapter14&15.ppt