transmutation transmutation is the process of atoms of unstable nuclide a changing into atoms of...
Post on 28-Dec-2015
Embed Size (px)
TransmutationTransmutation is the process of atoms of unstable nuclide A changing into atoms of nuclide B.This can occur naturally (by radioactive decay) or......as a result of bombardment reactionsExample: Bombardment of nitrogen-14 with alpha particles... oxygen-17 was formed.
Bombardment ReactionsThe production of synthetic elements (transuranium elements) and non-natural nuclides of other elements are the result of bombardment reactions.Example:208Bi + 4He --> 210At + ?14N + 4He --> 17O + ?
Chemical Effects of RadiationRadiations produced from radioactive decay can interact with atoms and molecules of surrounding material.Electrons of these atoms/molecules are most directly affected by radiation.ExcitationIonizationTypes of radiation:Nonionizing - excitation (low energy)Ionizing (high energy) - resulting in formation of ion pairs
Free Radical FormationFree radical: atom, molecule or ion containing an unpaired electronFree radicals rapidly react with nearby chemicals.Stable moleculeAnother free radicalExample:H2O + radiation --> H2O+ + e-H2O+ + H2O --> H3O+ + OH (hydroxyl radical)
Radiation Effects on the Human BodyProtection?:paper or clothingmetal foil (such as Al)thick concrete & Pb
Biochemical Effects of RadiationAlpha - due to ingestionExample: polonium-210 (t1/2 = 138 days)
Beta - both internal and externalExample: iodine-131 (t1/2 = 8.0 days)cobalt - 60 (t1/2 = 5.3 years) skinburns
Gamma - this is very effective!!Alpha, beta, and gamma radiation differ in penetrating ability.
Radiation DetectionFiltersExample: Film badges used in nuclear power facilities
Geiger countersContain gas atoms which are ionized...Film badges are used to determine a persons exposure to radiation.Radiation passing through a Geiger counter ionizes one or more gas atoms, producing ion pairs.
Sources of RadiationNaturalRadon seepage, rocks & soils, minerals in the body, cosmic radiation.Human-madeMedical X-rays, nuclear medicine, consumer products, occupational exposure, nuclear fallout (from weapons testing and nuclear power plants)
Cells that reproduce rapidly are most sensitive to radiation damage.
Nuclear MedicineDiagnostic uses: use a radionuclide of an element already present in the bodyThe movement of the radionuclide is easily monitored.
Brain scans are obtained using radioactive technetium-99 (emitter), a laboratory-produced radionuclide.
Therapeutic Usesused to selectively destroy abnormal cells
Fission & Fusion reactionsFission: a large nucleus splits into two medium-sized nuclei with the release of several free neutrons and LOTS of energy.
Fusion: two small nuclei are collided together to produce a larger nucleus and LOTS of energy.
FissionUranium-235 undergoes fission when a neutron collides with the nuclide.
If enough radionuclides are present, a chain reaction can occur. Watch out!
Fission Nuclear ReactorsThe fission reactor produces heat that is used to turn water into steam in order to drive a turbine.
The benefits include a large amount of energy from a relatively small amount of fuel.
The potential risk includes:Disposal of radioactive productsFallout if an explosion occurs
FusionNaturally occurs in stars!Consider what happens during a stars lifetime!
Ex.1H + 2H --> 1H + 3H -->
Benefits: Nearly unlimited fuel supply; no radioactive wasteRisks: Very difficult to maintain the reaction (need extremely high Temperatures to keep the reaction going)
The process of nuclear fusion maintains the interior of the sun at the temperature of approximately 15 million degrees.
Comparing Chemical & Nuclear Reactions