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Unformatted text preview: Chapter 25 Nuclear Processes Quiz: Did you read Chapter 25 for today? ) es a) Yes b) No Earth But first… From the BBC: s Remember van der Waals or dispersion forces? Apparently they are the most important force in holding geckos to walls. Weird Interactions s Recall there are four in the universe: • Gravity • Electromagnetic • Nuclear Weak uclear Strong • Nuclear Strong s We’ve studied the first two. Now we will learn about the two nuclear ones. Nucleons s Both protons or neutrons are called n u c l e o n s . s Protons feel both the attractive strong nuclear force and the repulsive electromagnetic force. s Neutrons only feel the attractive strong nuclear force. Force equations s Gravity: F = GMm/d 2 s Electromagnetic: F = kQq/d 2 s Strong Nuclear: F = ?? • We do not yet have a single equation for the Strong d M m d Q q d N n Nuclear force! But we know it is VERY short range. s Weak nuclear: F = ?? • Theories called Grand Unified Theories (GUTs) say that it is really a manifestation of the electromagnetic force… Still more work to be done… Atomic and Nuclear Models s Electron energy levels have been measured experimentally • Emission spectra. s Patterns were recognized. his led to the Bohr model s Nuclear energy levels have been measured experimentally. • Gamma rays cientists are still looking Atomic Nuclear This led to the Bohr model s We have a working Quantum Mechanical model. s Electron energies can now be calculated exactly using electric force laws and equations for wave behavior. s Scientists are still looking for patterns. s We have pieces of a quantum mechanical model. • There are still some holes. s We cannot yet calculate exact values for nucleon energies. Atoms and Isotopes s Atomic number = number of protons. • This is what makes an element unique. s Mass number = number of nucleons. s Mass number = number of nucleons. • Different isotopes have different numbers of neutrons....
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This note was uploaded on 11/30/2011 for the course PHY S 100 taught by Professor Staff during the Winter '08 term at BYU.
- Winter '08