What Causes and Crosses Orbital Nodal Forces?

[Oblivion]

I am wondering what forces cause the nodes between orbitals to occur, and if these nodes are ever penetrated or crossed by electrons during exitation of the atom.

 

[quantum]

Nodes eh? That's not quite the way I understood the structure of an atom. You see, Bohr-Rutherford diagrams and such are much different than the real thing. Infact, a theory of quantum mechanics suggests that electrons for an atom here on Earth may currently be on mars, or vice-versa.

 

[Oblivion]

Yes however, I am asking about the nodal surfaces that form for all p,d, and f orbitals and pass through the orgin of the xyz axis. These nodes occur on boundary surface diagrams for electron density.

 

[Bystander]

If you are really, really, really desperate, and willing to give me a couple days, I can dig up reference(s) to "zero probability nodes" to which you refer, and the fact that they are NOT really zero --- you are being given maps of the "shortcut" solutions to the Schrödinger Eq. when you see the pretty pictures in the general chem. texts --- if you do not specifically request further ref., I'm going to drop this right here --- I do NOT like QM, I have not messed with it for years, and I "really, really, really" don't want to go digging.

 

[Oblivion]

No, that's ok. I've just been pondering them for sometime and don't understand how an electron in an exited atom can essentially go from one orbital to the next, without actually passing through the space between the orbitals. Thanks for the reply.

 

[Chemicalsuperfreak]

OK. This is some weird stuff for people who haven't seen the math in a proper class. Do you know what a wavve function is? It describes where you are likely to find a particle in around an atom. Consider a one dimensional box. Just think of it as a very skinny slot that an electron can fit down into. Drawing a graph may help. Your x-axis is the length of the box going from zero to L (the opposite end of the box). The Y-axis is the probability of finding the electron (actually it's the square of the wave function). The wave function for an electron is a sine wave, it starts at 0 (almost) probability on one side of the box (x=0) reaches its maximum at 0.5L (you're most likely to find the electron in the middle of the box), and falls back to zero (almost, it's a weird phenomenon, gives rise to tunneling, don't worry about it for now) at L. The length L will be one half wavelength with respect to the wave-function. When you solve for the electron in three dimensions you get a nice even sphere. With p-orbital electrons you get a different wavefunction. You also start at y=0 at x=0, but it is one full wavelength in the box, that is the wave function rises to it's peak at x=.25L, falls back down to 0 at x=.5L, goes down to a minimum at x=0.75L, and goes back to zero at x=L. Remember,probability is the square of the wavefunction, so when it's squared the wavefunction in the negative becomes positive, but 0 squared is still zero, at the probability is still 0 at x=0.5L. So you've basically got two bumps at x=0.25 and x=0.75L where you are likely to find the electron and a node right in the middle where you don't find the electron at all. When solved for three dimensions, the p-orbital gives the dumbell shape. When you solve for the d-orbital you change wave functions again (giving a crest, trough, crest) which results in two nodes. And you get three nodes with the f-orbital.

Hope this didn't confuse you worse.

 

[Chemicalsuperfreak]

Originally posted by Oblivion
No, that's ok. I've just been pondering them for sometime and don't understand how an electron in an exited atom can essentially go from one orbital to the next, without actually passing through the space between the orbitals. Thanks for the reply.

Guess I should have read this post before I replied to the topic. The space between the orbitals are different then the nodes. Using my previous analogy of the particle it the box. The wavefunction doesn't go to zero at x=0 and L like it does at the node. At the wall of the box, the wavefunction is slightly above y=0. It passes through the limits and decreases exponentially, but never actually reaches zero,due to the Heisenberg Uncertainty principle. You can never keep a particle completely in the box. So the particle can tunnel through the side of the box and into another. When you excite an electron into a higher orbital it actually tunnels.

 

[zainab]

nodes

If you are really, really, really desperate, and willing to give me a couple days, I can dig up reference(s) to "zero probability nodes" to which you refer, and the fact that they are NOT really zero --- you are being given maps of the "shortcut" solutions to the Schrödinger Eq. when you see the pretty pictures in the general chem. texts --- if you do not specifically request further ref., I'm going to drop this right here --- I do NOT like QM, I have not messed with it for years, and I "really, really, really" don't want to go digging.[/QUOTE]

 

[zainab]

nodes

I wouled like to find up reference(s) to "zero probability nodes" and the fact that they are NOT really zero.