Energy gap

[Alexandra Salata 2L]

Dr Lavelle drew a diagram when he was explaining the energy levels in H-atoms. he said that all spectral lines showing up in the UV region involve the energy gap n=1 and n=2. Why is this? Is it because it has the highest energy difference?

[Sid Panda 3A]

Dr Lavelle drew a diagram when he was explaining the energy levels in H-atoms. he said that all spectral lines showing up in the UV region involve the energy gap n=1 and n=2. Why is this? Is it because it has the highest energy difference?

Yes you are correct. The highest energy difference is between n=1 and n=2. Because there is such a high energy difference between n=1 and n=2, that must mean that the frequency of photons emitted from an electron going from n=2 to n=1 must be high as well. This is because of the equation E=h*v, where h is Planck's constant and v is the frequency of the light.

If E is high, then v must be high. Higher frequency means lower wavelength and those lower wavelengths usually correspond to the UV region of light.

Hope this helps!

[Andrew Wang 1C]

In addition to what Sid posted, the spectral lines in the UV region are part of the Lyman series, which has n₁=1 for its lower energy level and n₂=2 as its higher energy level, which is why they have higher energy and a shorter wavelength.

[Gina Spagarino 3G]

n=1 and n=2 has the highest energy difference since it is the biggest gap; the UV region involves this gap, but is not limited to only being between these 2, as long as this gap is included. The UV region includes electrons in n=2, n=2, n=4, n=5, etc & returning to ground state(n=1), which is the Lyman Series.

[Tae Pasawat 2A]

I have another question, since we mainly look at the energy level an electron falls down to to dictate what series it belongs to, Professor Lavelle emphasized that this is because the energy level it falls down to gives a good idea of the energy difference. If, for example, an electron falls down to n=2 and the energy difference is bigger than that of an electron falling down to n=1, do we still look at the energy level it falls down to or the size of the energy difference?