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Atomic Fingerprints

Atomic Fingerprints.

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Atomic Fingerprints

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  1. Atomic Fingerprints

  2. In the Bohr model of the atom, electrons can be found only in certain energy levels. Electrons “jump” from one level to the next without passing through any of the regions in between. When an electron moves from one level to another, it gains or loses energy, depending on the direction of its jump. • Bohr’s model explained an unusual event. When electric current flows through a gaseous element, the gas produces a glowing light, like a neon sign.

  3. If this light is passed through a prism, a pattern of lines appears, with each line having a different color. The pattern depends on the element- neon has one pattern and helium another. What causes these lines and why are they always the same for a given element? • In Bohr’s model, the lines are caused by electron jumps from higher to lower energy levels. Because only certain jumps are possible, electrons release energy only in certain quantities. These packets of energy produce the lines that are seen.

  4. Because the energy levels in each element are different, each element has a unique set of lines- a sort of atomic fingerprint. These lines can be used to identify known elements. This method is often used to identify gases in a mixture, and can be used to determine the chemical composition of stars and interstellar gases.

  5. Questions • What limitation is placed on electrons in the Bohr model of the atom? • When the light from a gas is passed through a prism, why is there only a certain number of lines rather than a continuous spectrum? • How is the series of lines emitted by a gas similar to a fingerprint? • Why is it important to be able to identify unknown gases on earth and in space?

  6. Activity • Design a lab that uses the information covered in Atomic Fingerprints. • You will need a problem, hypothesis, variables, materials, procedure, and a chart set up for your data. • Turn in at the end of the period. • I have started working on the tests and should have them ready for you on Friday along with some other new things.

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