# Trouble Understanding Suborbitals

1. Feb 22, 2017

Hi. I'm currently taking my first chemistry course in at a college level. I'm still a bit new to it, alongside the fact that I missed a few weeks due to being out of town, but I'm excited to get into it. I want to have one of those "AHA" moments like I've experienced with math. Only thing is it seems to be quite a bit tougher. Right now I'm still trying to learn orbitals, suborbitals, and reading the Periodic Table of Elements.

One of my homework questions is asking me which of these orbitals has the highest energy: 4px, 3px, 2px, and 5px. I am guessing that it would be 5px assuming that we're still at a higher level orbital, but what about ionization, atomic radius, and electronegativity? How can I take all of these into account. Sorry if my question seems broad, but I'm honestly still trying to figure out where to start, and how I can visualize this and process it more efficiently. I'm lost...

2. Feb 23, 2017

### DrDu

At least in hydrogen, the energy depends only on the main quantum number n as $E\sim -1/n^2$. In many electron atoms, the energy also depends on the angular momentum quantum number, as orbitals with a lower angular momentum have a higher probability to be found near the nucleus where the charge of the nucleus is less shielded by the other electrons. Hence attraction and binding energy is also stronger.
According to Koopmanns theorem, the ionisation energy is approximately the negative of the energy of the highests occupied orbital in an atom.
The electronegativity according to Mulliken is proportional to the average energy of the highest occupied and the lowest unoccupied orbital.