Good quantum physics question help please??????????????????????

Okay can someone explain to me how:
1. how does an atoms electron gain the energy to enter a forbidden state/transition and how does it loose the energy to come from this state

Often it is coupling between the rotational, vibrational, etc. energy levels which is usually ignored
That is, while a "pure" energy state is one mode, in the real world they are mixed and have just ONE quantum mechanical equation. We separate terms to keep the math easy to work with (and as an excellent first approximation - for low mass atoms at low energy)
There's is no good answer to your second question
possibilities (among others) are:
1. That's just the way the Universe works, particles seek lowest energy state
2. The Laws of Thermodynamics
3. Entropy

sorry I assume you already know that the energy is from either absorbed photon(s) or collisions or couplings - I assumed your puzzle was for the forbidden absorptions/emissions

might want to repost this in Chemistry

The energy has to come from some external source. Usually, we talk about the electron being "hit" by a photon, and the energy from the photon bumps the electron up to the next permissible state. Similarly, if the electron "falls" from a high-energy state to a lower-energy state, it will release a photon in the process.

Electrons gain their energy by electromagnetism that's how they spin and orbit the nucleus of an atom. Differebt elements have electrons in diffrent oribitals so its not something hitting it, its rather the structure of the nucleus that determines the state of the electron.

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