Unit 3 Notes 16-17 Kim.pptx - Unit 3 Atomic Emission...

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Unit 3 Atomic Emission Spectra Electron Configuration Periodic Trends
Atomic Emission Spectra
Niels Bohr’s theory of quantized energy levels Electrons are found only in certain allowed energy levels in the electron cloud The farther from the nucleus, the higher the energy level
Different Energy States are Possible Electrons are naturally found in their ground state When the electrons in an atom become excited by absorbing energy from the surroundings, they jump to new, higher energy levels. This is called the excited state The excited state is less stable than the lower energy state, therefore the electron falls back or returns to the lower energy ground state.
Return to Ground State When electrons fall back a specific amount (quantum) of energy is emitted The energy is given out in the form of a photon of light If we see color, then the emission is in the visible range We perceive this as unique colors associated with particular elements
How electrons change energy levels When energy is absorbed: Electron moves from ground to excited When energy is released: Electron moves from excited to ground
Examples Copper compound heated in a flame Electrical charge passed through a gas
R O Y G B I V Electromagnetic Spectrum
Electromagnetic Radiation is Energy in Waves The length of the wave is inversely related to its energy Speed of light = wavelength x frequency (ms -1 ) (m) (s -1 )
Wavelength Violet light =shorter wavelength, but higher energy Red light = longer wavelength, but lower energy Draw me! Draw me!
How is Light Energy related to Color? White light is made up of all colors of the spectrum When passed through a prism a continuous spectrum (rainbow effect) is obtained
Elements Emit only Specific Wavelengths Individual elements emit a spectrum containing discrete lines This is called a line spectrum
Hydrogen Emission Spectrum
Hydrogen Emission Spectrum
Bright Line Emission Spectrum Element X smaller wavelength higher wavelength higher energy lower energy Each line corresponds to the energy emission when an e - falls from excited to ground state Lines closer together at higher energy indicating a smaller energy difference between levels farther away
How Line Spectra Relates to Atomic Structure #1. Electrons exist in distinct energy levels Each line represents the energy emitted as an electron falls from the excited state to the ground state
What Line Spectra Tell Us About Atomic Structure #2. Energy differences are smaller between levels that are farther from the nucleus Evidence of this is that the lines are closer together on the higher energy end of the spectrum

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