orbits and subshells confusion

Woopydalan

I was reading my textbook and was confused on the terminology, is an orbit each of those boxes that you fill up with the up and down arrow, and the subshell is like s, p, d, f, g, h?

I was also confused about what the shielding effect is.

If anyone can enlighten me that would be great, thanks

chemisttree

The up and down arrows denote the electrons themselves. The arrows represent the angular spin of the individual electrons. The boxes are representations of the subshells within the particular 'shell' or principal energy level. Sometimes the principal energy levels are drawn as circular 'orbits' but the electrons don't really orbit the nucleus. They reside in regions of space that trace out various shapes like spheres, dumbells and so forth.

Electrons in the outermost 'shells', being negatively charged, have a columbic attraction to the positively-charged nucleus. The magnitude of that attraction is governed by the number of protons present in the nucleus (obviously!) and the effectiveness of the lower lying electrons in their 'shells' to screen that positive charge. After all, the negatively charged outer electrons are both attracted to the positively-charged nucleus and repelled by the negatively-charged inner shell electrons. The net effect is that the outermost electrons still are attracted to the positively-charged nucleus but the magnitude of that attraction, or Z[sub]eff[/s], is diminished somewhat. It's called the shielding effect.

Woopydalan

Ok so a shell is s, p, d, f, g, h? And a subshell is each one of the boxes. Meaning, the P shell contains 3 boxes or subshells? And the orbit is another name for shell?

chemisttree

No.
Yes.
Try this.

Woopydalan

Ok wow so I have thought this whole time that the electrons travel in circles around the energy levels haha.

Ok so my understanding of that article then is that the s,p,d,g,f are actually orbitals? Then 1s,2s,2p, etc are shells?

Borek

Orbital is ambiguous - for example it can mean both 2p or any of 2p_x, 2p_y or 2p_z.

Shell is something larger.

Woopydalan

ok so 2p is an orbital, the box is a subshell, then what is a shell??

Borek

Yes, no, http://en.wikipedia.org/wiki/Electron_shell

Woopydalan

Why did the other guy say the box is a subshell and now you say its not a subshell. No wonder I'm so confused, you chemists can't make up your mind!

Ok so the wikipedia article says K, M, etc are shells (which are associated with l), and the subshells are s,p,d,g,h,f. Then what are the orbitals? Are those the boxes with the up and down arrows?

Borek

English is my second language and I am not 100% sure about the exact meaning of a subshell. As I wrote before - orbital is ambiguous and can mean two things. Perhaps subshell is just a synonym of orbital (so it can be both a single box, or collection of boxes), but I was always under impression that subshell is a "large" orbital, so it can mean 2p, but not 2p_x.

Woopydalan

ok my book makes it sound like s,p,d,g,f,h are subshells, which jives with what you were saying. Orbital you said was ambiguous, now what is a Shell (NOT SUBSHELL!)? Or a shell is n=1, n=2, etc?

Borek

Yes.

Woopydalan

alright thanks! It only took me 11 posts and 2 professional chemists and a lot of headache to figure out that little concept :P