# Color from D-Orbitals

Discussion in 'MCAT Study Question Q&A' started by justadream, Sep 6, 2014.

1. ### justadream 7+ Year Member

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Is it from absorption of energy from d-orbital electrons or the EMISSION of energy (after first absorbing it)?

2. ### Cawolf 5+ Year Member

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I may be misunderstanding your question, but in general emission spectra are from a decrease in energy level (emission of energy) and absorption spectra are from an increase in energy level (absorption of energy).

3. ### justadream 7+ Year Member

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@Cawolf

Gotcha. A question I ran into made it seem like the absorption caused the color.

4. ### Cawolf 5+ Year Member

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Ah ok.

Yah when electrons decrease in energy by a discrete amount, the energy is released as an EM wave with a specific wavelength based on the quantum of energy.

5. ### justadream 7+ Year Member

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@Cawolf

I think I asked this once in one of my threads before but I think the answer was unclear and/or I forgot the answer.

Let's say an electron can reach energy level 1 (which is higher than the ground state energy). Do you need to excite the electron with an amount of energy exactly equal to the difference between the ground level and energy level 1?

If not, why not? Since energy is "quantized", does the electron just like reach halfway between energy level 1 and 2 and then fall back to energy level 1 (since it lacks energy to reach level 2)?

6. ### Cawolf 5+ Year Member

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Yes, it will only absorb a quantized amount of energy.

So white light shined on this electron will produce an absorption spectra with a black line based on energy absorbed.

As far as I know, if the energy is not a match to the discrete energy levels available to the electron, the energy will pass through without interaction.

7. ### justadream 7+ Year Member

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@Cawolf

Is there such thing as "margin for error"?

Like in real life, the energy needed is gonna be some random number like 5.2344209138490348912384029183434 units of energy. If it's off by like 10^-20, is it really not gonna work?

8. ### Cawolf 5+ Year Member

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My highly limited understanding of quantum theory would say no - discrete is discrete.

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