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General chem queries


amalwa12

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Hey guys,

 

Any help on this question is appreciated:

 

When an electron in a Hydrogen atom transitions from the third to second energy level, a photon with a wavelength of 656nm (orange light) is emitted. A transition from the second to first level most likely results in a photon emission from which region of the electromagnetic spectrum?

 

A. Red visible light

B. Infrared

C. UV

D. Micro-wave

 

Answer: C

 

I have no idea how to reach this answer. Please help! :)

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Hey guys,

 

Any help on this question is appreciated:

 

When an electron in a Hydrogen atom transitions from the third to second energy level, a photon with a wavelength of 656nm (orange light) is emitted. A transition from the second to first level most likely results in a photon emission from which region of the electromagnetic spectrum?

 

A. Red visible light

B. Infrared

C. UV

D. Micro-wave

 

Answer:

 

I have no idea how to reach this answer. Please help! :)

 

Hey Amalwa12. I think this is becuase when atoms move from a higher energy level to a lower energy level, they emit fluorescence and fluorescence emissions usually fall in the UV range (I think).

 

 

Hope that helps!

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When an electron ABSORBS photon of the correct frequency, the electron goes to a higher energy level in the atom and is said to be in an EXCITED STATED. Now...when the electron comes back down to the more stable state, i.e. GROUND STATE, it releases a photon. This photon, in theory, can have the SAME EXACT frequency as the photon that was absorbed (Scenario 1)...OR the frequency of this photon will be less than the photon which was initially absorbed (Scenario 2 - This is what happens in UV-VIS Spectroscopy). Keeping the equation "E=hf" in mind...you can see that the lower frequency means lower energy.

 

Keeping the facts stated above in mind, when you look at the answer choices...the correct answer choice should be the one that has MORE ENERGY or the SAME ENERGY as the photon that was emitted. In this case, since an orange photon is emitted...this means that the correct answer should have energy that is equal to orange photon, or greater (due to scenario 1 and 2). Microwave and infrared can immediately be crossed out; Red has less energy than orange, since it is the longest wavelength photon in the visible spectrum. The only choice you are left with is C, UV.

 

Hope that helps!

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hmm ok, transitions in hydrogen from 1 to 2 always take more energy than 2 to 3, and 2 to 3 takes more energy than 3 to 4. Basically the transitions farther from the nucleus take less energy than those closer. The inverse is alway true, the released energy is greater when excited elections fall from 2 to 1 than from 3 to 2.

 

You know the drop from 3 to 2 releases orange light, so the drop from 2 to 1 must release something with higher energy than that. The only choice given that does that is UV light.

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hmm ok, transitions in hydrogen from 1 to 2 always take more energy than 2 to 3, and 2 to 3 takes more energy than 3 to 4. Basically the transitions farther from the nucleus take less energy than those closer. The inverse is alway true, the released energy is greater when excited elections fall from 2 to 1 than from 3 to 2.

 

You know the drop from 3 to 2 releases orange light, so the drop from 2 to 1 must release something with higher energy than that. The only choice given that does that is UV light.

 

+1 :) exactly how I did this question/similar questions when I was studying!

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