7.2 Summary Notes - Atomic Spectra & the Qunatized Model Flashcards
The Bohr Atom
Developed by Bohr.
Experimental evidence.
The light produces is analyzed using a prism or diffraction grating. Continuous Spectra is observed when a solid is heated, line-absorption Spectra is observed when white light is passed through a gas at low temperature, line-emission Spectra appears when hot gas emits energy.
Interpretation of evidence:
Electron energy when orbiting a nucleus is quantized. The those energy levels Maxwell’s law stating that accelerating charges must emit does not apply. When electrons absorb energy they move to higher energy levels, when they release energy as a photon they move to lower energy levels. Only certain frequencies and wavelengths can be emitted or absorbed by an atom.
Spectra
The light produced by various substances.
What are the three types of spectra?
Continuous Spectra, line emission spectra, line-absorption spectra
Continuous Spectra
When a SOLID is heated it will produce a continuous spectra (blackbody radiation)
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Line-emission Spectra
When HOT GAS emits energy a bright line Spectra is observed. Each element has its own characteristic line emission spectrum which may be used to identify the elements.
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Line-absorption Spectra
WHITE LIGHT (a continuous spectra) is passed through a gas at lLOW TEMPERATURE. A spectrum with lines of missing wavelengths (dark lines) is produced.
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When is a line-emission spectrum produced?
When the electron in an atom releases energy as a photon.
When is a line absorption spectrum produced?
When the electron in an atom absorbs photon energy.
