Transcript Slide 1
We get a planetary view of the atom Nucleus 1/10,000 atoms diameter 99.9% of atoms mass is in the nucleus BUT.....!!! An orbiting electron must be accelerating…..WHY??? Changing direction So, it must radiate energy….WHY? Accelerating charges cause EM radiation KE & Momentum should be lost due to E-M radiation. Electron should spiral inward to nucleus 62 52 42 n=32 n=6 n=5 n=4 n=3 (2nd excited state) n=2 (1st excited state) Larger Jump = More Energy = Bluer Wavelength n=1 (Ground State) 26 25 24 n=23 n=6 n=5 n=4 n=3 (2nd excited state) n=2 (1st excited state) Photons of all other energies (wavelengths) are ignored and pass on by unabsorbed. n=1 (Ground State) Hydrogen Helium Oxygen Neon Iron Nebula NGC 2363 This nebula is a glowing gas cloud about 10,000,000 LY from Earth. The hot stars in the Nebula emit high energy photons that are absorbed by the gas. The heated gases produce an emission spectrum and the particular wavelength of the red light of the nebula is 656nm. The exact wavelength of Hydrogen. The Suns Absorption Spectrum The Suns Absorption Spectrum from 420 – 430 nm. (TOP) The emission spectrum of Iron (Bottom) In the late 1800’s astronomers were trying to organize and make sense of all the data they were collecting. At the time, spectra studies were the most reliable, but there is a huge diversity of stellar spectra. In 1870’s stars were classified into various letters based upon their spectral patterns. Hydrogen Balmer Lines Very Weak due to extreme temps Hydrogen Balmer Lines Strongest Hydrogen Balmer Lines fading out and trace amounts of heavier elements starting to appear Stars containing heavier metals such as Calcium and Iron (Including the Sun, a G2 star) Stars containing Titanium Oxide In short, the OBAFGKM system allows us to Identify the surface temperature of the stars Chemical composition of the stars 2.9 x103 max ( meters ) T ( Kelvin) So we can determine the distances and characteristics of Stars We need a better classification scheme Where 4πR2 = area of a sphere