Lecture11_AtomicStructure1

Lecture11_AtomicStructure1 - Physics 126 Lecture 11 March...

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S.Du Sp2011 1 Physics 126 Lecture 11 March 14&16, 2011 Atomic Structure (Quantization of Atomic Energy Levels) The nuclear atom Electron orbits Balmer and Rydberg Series Atomic spectra Bohr model Reading: Chap 4: 4.1 – 4.4 Shengwang Du
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S.Du Sp2011 2 Two Broad Themes: What is Matter? What is Radiation (light)? What is Matter? Electrons, X-Ray, Radioactivity, atomic nature of matter, atomic nucleus ( Quantization of Matter) What is radiation (including light, infra red heat wave, etc)? Statistical Mechanics and Radiation (light): Energy is ‘quantized’ Quantization of Light . Atomic Spectra and the Bohr atomic model Quantization of Atomic Energy Levels. X-Ray diffraction and X-Ray spectra . Radiation (light) is wave ! Compton scattering Radiation is particle! Einstein’s quantum theory of radiation. Radiation is particle with energy and momentum! Particle – Wave duality for light Matter is wave . Particle – Wave duality for matter The New Quantum Mechanics
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S.Du Sp2011 3 Basic properties of atoms ± small: ~ 0.1 nm (10 -10 m) A crude estimate: Iron has a density 8 g/cm 3 and molar mass 56 g. So one mole (~6x10 23 ) of iron atom has a volume of 7 cm 3 and one iron atom occupied a max. volume of 7/6x10 23 ~ 10 -23 cm 3 . The diameter is then about 10 -23/3 ~ 2x10 -8 cm=0.2nm. impossible to see an atom using visible light ( λ ~500nm) ± atoms are stable. ± contains negative charges: external disturbance can expel electrons from atoms, e.g. Compton effect and photoelectric effect. ± an atom as a whole is neutral. ± atoms can emit and absorb EM radiation. How? Any atomic model must explain this! A ‘Model’ is a simplified (mathematical) description which can make definite predictions.
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S.Du Sp2011 4 What is an atom?-- History ± Early Greek philosophers: " τομος "— átomos (from α -, "un-" + τέμνω temno , "to cut"), means uncuttable, or indivisible. ± 17th & 18th centuries, chemists showed that certain substances could not be further broken down by chemical methods.
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This note was uploaded on 03/31/2011 for the course PHY 126 taught by Professor Hobunchan during the Spring '11 term at HKUST.

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Lecture11_AtomicStructure1 - Physics 126 Lecture 11 March...

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