Rydberg Equation [ENDORSED]

[Vincent Chiang 1L]

In the Rydberg equation, does (n1)^2 always have to be the lower energy level? Or can it be the first given energy level (for example if the problem says it went from energy level n = 4 to n = 2, can n1 be 4)?

[Chem_Mod]

Hi Vincent,

That's correct. Depending on whether light is absorbed or emitted, energy levels can either increase or decrease, respectively.

Hope this helps.

[alyssawhite1L]

This question is largely why Lavelle would prefer we use the equation E = -hR/n^2 and couple it with the equation ΔE=Efinal-Einitial. This way you never have to be concerned about whether or not to use the higher energy level. You only have to know which energy level it started at (initial) and which it ended at (final).

[Jacquelyn Hill 1]

If the problem says that it went from n=4 to n=2, does that mean 2 is the final? Or is 4 the final since it is the higher energy level?

[Lily Guo 1D]

If the electron is going from n=4 to n=2, then n=2 would be the final energy state and n=4 would be the initial energy state.

[mayasinha1B]

If the electron is going from n=4 to n=2, then it would be going from an excited state to a lower energy state, which would make sense that the resulting Energy from the Rydberg equation would be negative, as energy would be emitted in this scenario. In the equation, n1 is the initial and n2 is always the final, and the equation works itself out to whether the resulting energy is positive or negative.

[JamesAntonios 1E]

Rydberg's Equation describes the change in energy. Change is always final-initial, except in very few specific cases.