radioactivity nucleus – center of the atom containing protons and neutrons –how are the protons...

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Radioactivity

RadioactivityNucleus center of the atom containing protons and neutronsHow are the protons and neutrons held together?Strong Force - an attractive force that holds protons and neutrons togetherThe protons and neutrons must be close together for this force to keep them togetherAs the nucleus increases in size, the strong force diminishes and the electrical force (force between charges) becomes more powerfulRadioactivity process of nuclear (nucleus) decayStability of NucleiLarger nuclei are less stable all nuclei that contain more than 83 protons are radioactiveThe ratio of neutrons to protons also determines if an element is radioactiveNuclei with too many or too few neutrons compared to protons are usually unstable, and thus, radioactiveNucleus numbers representationA nucleus can be represented by the following isotope notation

In this carbon-12 isotope, there are 6 protons and 6 neutrons, which makes it stable and not radioactiveWhat would carbon-14 look like?Would carbon-14 be radioactive? Why?C126element symbolmass numberatomic numberC146radioactive, because it has too many neutrons compared to its protonsNuclear Radiation when an unstable nucleus decays, particles and energy are emitted (given off)3 types of Nuclear RadiationAlpha ParticlesBeta ParticlesGamma RaysRadioactivity UsesTreating cancerInternal inspectionRadioactive dating of artifactsTracingSmoke detectorsSterilizationFood irradiationThickness monitoringNuclear energy

Alpha Particles made of 2 protons and 2 neutronsAlso known as a helium-4 nucleus with a charge of 2+ (no electrons)As the alpha particle leaves the atom, it passes through other matter and takes electrons, leaving behind ionsThis process causes it to lose much of its energyThe largest of the radiation types has an atomic mass unit of 4Least penetrating of radiations - can be stopped with a sheet of paper or clothingSymbolHe42Transmutation process of changing one element to another through nuclear decay- Alpha particle nuclear reaction

During the transmutation, the total mass and charges of the nuclei at the end are the same as the nucleus at the beginningPo21084Pb20682+He42+84+82+2Beta Particles a neutron decays into a proton and emits an electron in the processthe beta particle has a negative chargeSmallest of the radiation particles has an atomic mass unit of 0.0005Much faster and more penetrating than alpha particlesCan be stopped by a sheet of aluminum foil or woodSymbole0-1Beta particle nuclear reaction

During the transmutation, the total mass and charges of the nucleus and the electron emitted at the end are the same as the beginning-I13153Xe13154+e0-1+53+54-1Gamma Rays electromagnetic waveusually emitted from a nucleus when an alpha decay or beta decay occursgamma rays have no mass or charge and travel at the speed of lightDeepest penetrating of radiation, but is not as damaging to living tissue as alpha and betaRequires dense, thick materials such as concrete blocks or lead to stopAlpha particles have a greatercharge and mass than betaparticles and gamma rays do.Alpha particles travel about7 cm through air and arestopped by paper or clothing.Beta particles have a 1 or 1 charge and almost no mass. They are more penetrating than alpha particles. Beta particles travel about 1 m through air but are stopped by 3 mm of aluminum.Gamma rays have no charge or mass and are the most penetrating. They are blocked by very dense, thick materials,such as a few centimeters of lead or a few meters of concrete.

Radioactive Half-life the amount of time it takes for half of the nuclei in a sample of an isotope to decayExample, the half-life of (hydrogen-3) is 12.3 years.The H-3 will beta decay to He-3If a sample has 20 atoms of hydrogen, after 12.3 years, 10 atoms will have decayed to He-3, and the other 10 will still be H-3After 12.3 more years, another 5 will have decayed to He-3, and 5 will still be H-3H31

Radioactive Dating using known half-lives to date certain rocks, fossils, and other materialsCarbon dating radioactive isotope carbon-14 is found in plants and animals.Has a half-life of 5,730 yearsUsed to get the approximate age of plants and animals up to 50,000 yearsUranium Dating used to date some rocks that contain small amounts of uranium

nnnNuclear ReactionsNuclear Fission The process of splitting a nucleus into several smaller nucleiOnly large nuclei, such as uranium and plutonium, undergo fissionA neutron collides with a large nucleus and splits in twoSome of the mass actually converts to a tremendous amount of energynBa14256+ energyU23592Kr9036

Chain Reaction - When a nuclear fission reaction occurs, the neutrons emitted can strike other nuclei in the sample, and cause them to split. Nuclear Fusion two nuclei of smaller mass are combined to form one larger nucleusProduces even more energy than fissionTemperature must be extremely hot (millions of degrees Celsius) for nuclei to be moving so fast that they get close enough for fusion to occur+ energyH-1H-2He-3Nuclear Power FissionHow a Fission Nuclear Power Plant WorksEnergy comes from a controlled fission nuclear reactionUses Uranium -235As the nuclei split, tremendous heat is releasedHeat is used to produce steam that turns a turbine which rotates an electric generator

n +10U23592Sn +Mo +n1321015042103Nuclear Power FissionAdvantagesdoes not release pollutants like fossil fuelsprovides about a million times more energy per pound than fossil fuelsDisadvantagesradioactive material could be released into environment in an accidentdisposal of waste material is expensive and difficulturanium is non-renewableNuclear Power FusionHow Fusion Nuclear Power WorksFusion of 2 small nucleiHydrogen nuclei fuse to form HeliumMust occur at extremely high temperaturesReleases huge amounts of energy, even more than fission reactionsH +11e0-1He4242Nuclear Power FusionAdvantagesuses hydrogen as a fuel which is very abundant on earththe product is helium, a non-radioactive and non-polluting elementmost concentrated energy source knownDisadvantagesoccurs only at temps of millions of degrees Celsiususe more energy to produce the reaction than energy given offcontainment of the reaction will be extremely difficult

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