CHE 141 1st Edition Lecture 37Outline- Nuclear Fusion- Nuclear Binding Energies- Nuclear TransmutationNuclear Fusion- Nuclear fission is the splitting of a heavy nucleus to form two or more lighter nuclei- Nuclear fusion is the combination of two light nuclei to form a heavier one- Both fission and fusion release large amounts of energy because they form daughter nuclides with more binding energy per nucleon than the parent nuclides- Nuclear fusion is the energy source of stars and basis of hydrogen bombs- Step 1: 2 protons collide and fuse together to form deuteron and a positron- Step 2: protons fuse with deuterons to form helium-3 nuclei- Step 3: Fusion of 2 helium-3 nuclei produces a helium-4 nucleus and two protons- Hydrogen fusion produces energy in 2 wasy:o Annihilation reactions between positrons produced and electrons in the matter of surrounding the reactantsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.o Loss in mass as four protons are transformed into an alpha particle and two positrons - High temperatures are required to initial fusion as the initial step involves two positively charged nuclei to fuse together- Nuclei must be heated to the point where fusion can be initiated and sustained- Tokamak uses powerful magnetic fields to confine deuterium and tritium in the shape of a torus at temperatures over 10^8K, which produces a plasma where in some of the atoms are ionized- Nuclear fusion is also the basis of modern nuclear weapons called hydrogen bombs- A small fission bomb is detonated first, creating temperatures high enough for the subsequent hydrogen fusion Nuclear Binding Energies- Up to 56/26Fe, fusion reactions lead to products wither greater BE per nucleon than the reactants- Nuclides with Z<26 undergo fusion reactions that release energy- When heavier nucleus undergoes fission and breaks into smaller nuclei, the BE per nucleon increases- Nuclides with Z>26 undergo fission reactions that release energyNuclear Transmutation- Before chemists, there were alchemists, who sought the Philosophers stone in order to: transform base metals into noble metals, live forever (never very successful as they involved chemical reactions)- Nuclear transmutation the conversion of one chemical isotope or element into another- We have already seen this happen in both fission and fusion processes- Nuclear transmutation can be artificially induced by human interventiono Bombardment with alpha particles, neutrons, nuclei- Alpha bombardment requires alpha particles to be shot towards the nucleus at very high speed to overcome the electrostatic repulsion between positively charged alpha particles and positively charged nucleus- Linear accelerator increases the velocity of charged subatomic particles by subjecting them to a series of alternating electrical fields along a linear beamline- Cyclotron uses a combination of magnetic and electric fields to accelerate chargedparticles outwards from the center in a spiral
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