CHEM 213 Lecture Notes - Lecture 2: Boltzmann Equation, Gas Constant, Wavenumber
12 Sep 2016
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Document Summary
Uv or visible light promotes an electronic transition from the ground state e0 to an excited state e1. Photons are quantized, so you can not throw away any excess energy. Only absorptions that occur occur between accessible energy levels. Invent a stand in for frequency and call it wavenumber. Nacl doesn"t absorb in the region where organic molecules absorb. Salt plate always causes some scattering etc. so never 100% Find energy from wavenumber and previously learned equation. Stretching a bond is more energetic than just bending. Less energy to stretch bonds of heavier atoms. Lighter atom bond stretching higher energy. i. e. c-h. Big energy barrier, by pulling overlap of bonds apart. Characteristic of the bonds you have not the functional groups because lots of bends. Bend or stretch must have a dipole moment must change to be observed. Separation of charge the bigger the dipole moment. So n2, o2, ar do not give ir spectra (no dipole)
