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# Which has the greatest energy- a photon of infrared light, of visible light, or a ultraviolet light?

I am so lost! anything would help! thanks
Which has the greatest energy- a photon of infrared light, of visible light, or a ultraviolet light?
An electron de-excites from the fourth quantum level in the diagram above to the third and then directly to the ground state. Two photons are emitted. How does the sum of their frequencies compare with the frequency of the single photon that would be emitted by de-excitation from the fourth level directly to the ground state?

1. Well, the energy of a photon is directly proportional to its frequency. The greater the frequency, the greater the energy. E = hf
Ultraviolet light has a higher frequency than visible which has a higher frequency than infrared light.
As for the de-exciting electrons, conservation of energy is clearly important here. The sum of the energies of the two photons in the two step movement from level four to ground is the same as the energy of one photon emitted going directly to ground.

2. Ok so for the energy of a photon you have to remember a little about the electromagnetic spectrum. The shorter the wavelength, the higher the energy so: ultraviolet > visible > infrared so ultraviolet has the greatest energy.
For the second question we must remember that energy is conserved and it doesn’t matter how we get there, just where we end up. So, say when a photon goes from the fourth quantum level to the ground state (releasing energy because we are going from higher to lower energy states) that releases 5 energy units. Then say we have another electron that goes from the 4th to the 3rd quantum level it releases 2 units. Finally, that same photon goes from the 3rd to the ground state it releases 3 units. Thus, between the two photons, we have 5 energy units which is the same as the 1 photon that was simply more direct in its route. The bottom line is that it doesn’t matter what steps you take to get from point A to B because it will involve the same amount of energy as if you did it in one step.
Hope that helps!

3. UV light. Read the chapter in your book and stop asking people to do your homework questions for you. If you do not try to do them yourself, you will never learn anything.

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