# Need help

1. Mar 16, 2004

### bayan

i had a question about electrong moving to a higher level of energy.
When they do move to higher level energy do they get closer to nucie or do they move further from the nuclie (ie when forming a Photon.)

When sodium makes a yellow light would the wave length get smaller if an electron from a diffrent shell moves or does it get bigger?

i am doing year 11 physic and i asked this question to my teacher and he said that he wants me to find it out.
I know that he knew the answer but he wants me to find the answer.

2. Mar 16, 2004

Potential energy in the field of a nucleus for an electron is negative. The closer an electron gets to the nucleus, the more negative its potential. This means that the electron is bound, that it can't leave the potential well without energy being applied to it (to raise it to at least 0).

So a higher shell has a less negative energy, which is why when an electron falls from a higher shell to a lower shell, the difference in potential energy is emitted in the form of a photon.

That being said, we can think about the wavelengths of photons that are emitted when electrons change energy level. The energy of a photon is related to its wavelength by the formula

$$E = h\nu$$

So the greater difference in energy between the two states between which the electron is transferring, the greater the frequency ($\nu$) and the less the wavelength ($\lambda$), because

$$\lambda = \frac{c}{\nu}$$

So you tell me, which will result in a photon with a higher frequency, an electron falling from the n=2 level to the n=1 level or an electron falling from the n=3 level to the n=1 level?