[unsavedhero]

my textbook says that energy is emitted when an electron is added to an H+ ion and ends up in the n=3 shell.. but isnt energy absorbed when going into excited state?

[Corribus]

If you are adding an electron to H+, you are essentially starting from the n = ∞ state. If you end up in the n = 3 state, you release energy.  (This is the opposite of ejecting an electron already bound to a hydrogen nucleus, which requires energy.)  If your starting point is a neutral hydrogen atom in the n = 1 state, then you would be correct that energy would have to be absorbed to end up in the n = 3 state.

[unsavedhero]

thank you. that actually cleared it up. I forgot about the entire n = infinity thing