[amk0713]

Hello. To start, I am new to the forums, a college student, biology major with an emphasis on pre-med, and currently enjoy chemistry but occasionally have trouble fully understanding quantum mechanics.

To reiterate, what does an orbital actually look like? I understand that s, p, d, and f are the shapes of an electron's orbit, but what does that shape look like? For example, my book depicts the p orbital as an "8" looking shape, but does that mean that the electrons actually follow an "8" shape path? If so, how is that physically possible when the nuclear charge acts on the electrons? 

It's more of a visualization issue than understanding what it is.

Thank you for any help.

[nj_bartel]

 http://en.wikipedia.org/wiki/Image:Electron_orbitals.svg

Atomic orbitals are 3-d.  Stick an imaginary rod | through your 8, then rotate it about that rod.  That's what your p-orbital looks like.  Atomic orbitals are representations of 95% of the electron density - it's the most likely area for the electrons to be in.  It doesn't have to do with the path.

[amk0713]

So is the probability distribution of a 2p orbital inside the probability distribution of a 3p orbital? Is there a reason they are these specific shapes rather than a perfect sphere like in the s orbital or is it just a fundamental truth?

[Arkcon]

So is the probability distribution of a 2p orbital inside the probability distribution of a 3p orbital?

No.  Stare at the book a bit more.  The  1p, 2p, and 3p orbitals are visualized as being at right angles to one another.  Yes, that statement of mine is correct -- in 3 dimensions, 3 objects can be at right angles to one another, one of them is rising out of the page, bopping you on the nose and hitting you in the knees, if you will.

Is there a reason they are these specific shapes rather than a perfect sphere like in the s orbital or is it just a fundamental truth?

Yes. No.  I don't know.  Wait, what?  OK.  We do visualize them in that shape yes.  Do they really do that?  We can't really tell, that is the basis of the Heisenberg uncertainty principle.  We are blind people, trying to find a light bulb, hanging from a power cord, by swinging our white canes.  We're going to find it, eventually, but once we do, it won't be where we found it.  And why were we looking, anyway?

[enahs]

The p,d,f g,h, etc, orbitals are spherical.
That is, the sum of the p_x,p_y and p_z are spherical. The sub-orbitals, are however not spherical, and we can distinguish them via various spectroscopic techniques. The s orbital just has no sub-orbitals.
The shapes we have come up with are the best to mathematically explain what we witness.
Those shapes are also purely the angular aspect of the Schrodinger equation, it is not a complete story.

[azmanam]

If I can offer my 2 cents...

Think of it this way.  The electron doesn't follow a nice, planetary orbit like the cartoon pictures we learned in earlier classes.  The Heisenberg was mentioned earlier.  We can, with some accuracy, determine the position of an electron.  If we measure the position of an electron, we can plot it in 3 dimensions, and it will be a point at a given point in time.

If we measure the position at a different time, it will be in a different position.  Perhaps a little closer to the nucleus, perhaps not.  We can plot that point, too, and now we have 2 points where we determined the electron to be.

If we keep plotting the position of the electron, eventually it fills out a 3-dimensional shape - at least 95% of the time.  This shape that is created by plotting the position of the electron is the atomic orbital.

Orbitals aren't physical shapes... think of them as areas of high probability.  It is statistically probably that we will find an electron within the volume defined by the atomic orbital.

Try this, see if it helps...
http://www.upei.ca/~chem342/Resources/Reviews/Molecular_Orbital_Tutorial.pdf

The p,d,f g,h, etc, orbitals are spherical.
That is, the sum of the px,py and pz are spherical. The sub-orbitals, are however not spherical

Very interesting... I hadn't thought of it that way.  Makes sense, though.

[amk0713]

Thank you for all of the responses.

So a different quantum number doesn't necessarily mean a large shape? It's just a state of different energy?

Also, why do anti-bonds occur? Why did someone one day decide to subtract the probability distribution of two atoms?

[azmanam]

the pdf I attached answers the antibonding question.  It is a consequence of the linear addition of atomic orbitals.  You combine atomic orbitals by adding them together (constructive interference, bonding orbitals) and by subtracting them (destructive interference, antibonding orbitals)

[Yggdrasil]

The following thread may be useful in understanding bonding and anti-bonding orbitals:

http://www.chemicalforums.com/index.php?topic=25007.msg94470#msg94470

The key thing to remember is that electrons, like all quantum particles, behave like waves.  Thus, like waves, electrons can interfere both constructively and destructively.  Constructive interference of electrons give bonding orbitals while destructive interference of electrons give anti-bonding orbitals.