Electrons must absorb or release energy when moving to a farther shell?

Question

what about moving towards a closer shell?...do they need to release or absorb energy?

Answer 1

No no no...higher energy levels are closer to the nucleus, not farther.  The Zeeman Effect, where magnetic energy is pumped into electrons causes outer electron to jump to closer orbital shells.  Then, because that is an unnatural state for the higher energies, the electrons pop back out to their outer, normal shells.  

When they pop back out, they release the added energy through photon emission.  The photon energy can be observed as discrete bands in a spectrograph.   The farther out an electron normally is, the higher energy and, therefore, frequency it emits when resuming its normal orbit.  It emits the energy when going to the outer shells because it is losing energy.  The outer shells are lower energy levels.

There is a quick and dirty way to show the inner, not outer, orbits are the higher energy levels.  Use the Bohr model and the equations F = kq^2/r^2 for the centripetal force and C = mv^2/r for the centrifugal force on the electron as it revolves r distance from the nucleus. F = C when an electron q is in orbit at a fixed r radius.  (Understand the Bohr model is a simplification, but it does illustrate why higher energy is in and lower is out.)

F = kq^2/r^2 = mv^2/r = C; so that (1/2)kq^2/r = 1/2 mv^2 = KE, which is the kinetic energy of the q electron at radius r.  Note what happens to KE when r gets smaller...right, it goes up, which is why the energies of electrons closer in to the nucleus are higher.  If they were not, they would "fall" into the nucleus.

So discount those answers claiming the higher energies are farther away from the nucleus.  They are not correct.

Answer 2

Perhaps what eyesonthescreen discredits here is the attribution of the energy of an electron in a farther distance from the nucleus to the Kinetic kind. Indeed, if this is so, then we must second the argument of eyesonthescreen, so that the energy that is increasing with distance is not the kinetic, but rather the potential.

For the original question, the photoelectric effect may provide a small amount of understanding. In the photoelectric experiment, light with considerable energies are directed upon a conducting material (a metal perhaps) and an electric current detector is attached to this conducting plate (one may envisage this system as an electrical circuit). It is found that a current is existent in the metal when light is shed upon the surface, implying that electrons bound on the surface of the metal are liberated from the nuclear potential (hence allowing for their motion around the circuit).

The extension of the implications of this experiment can be extended to the shell levels of an atom. As light impinges on an innocent electron, the electron absorbs the energy carried by the light (photon) and must therefore gain potential energy, which consequently requires the increase of the electron's distance from the nucleus.

However, from quantum theories, the phenomenon of light production from atoms are caused by those electrons which return closer to the nucleus (photon emission).

(The above effects are dissimilar from the examples of eyesonthescreen, such anomalies are exactly the complications faced by Quantum Mechanical phycisists)

Answer 3

The electrons on the outer shells have higher average energy.  So they must absorb energy when moving to a farther shell.  And visa versa.

Answer 4

Absorb energy to move away from the nucleus. Release energy to move down.