Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne F Orbitals
Name:  peter tran
Status: N/A
Age: N/A
Location: N/A
Country: N/A
Date: 1999 


Question:
Can anyone answer this question? The question is on F Orbitals. Please tell me how this looks like. I've gone to many libraries but I cound't find anything.



Replies:
You have asked a very difficult question. First, because it requires a verbal written response rather than a face-to-face interaction with a blackboard that we can draw on, and secondly because most of us have probably never seen drawings of f-orbitals. After all, drawings are only two dimensional and the orbitals are 3-d, well 4-d since there are three coordinates (x,y,z) and the magnitude of the orbital. It is very difficult to draw 4-dimensional objects on a 2-d paper. To make it easier, one convention is to try to represent the orbital as a funny shaped balloon that would "contain" a certain amount (say 95%) of the electron density of the selected orbital. Using this convention an s-orbital looks like a perfectly round ball. Any of the p-orbitals (there are 3 of them) look like two sno-cones arranged so the cups point directly at each other. The d-orbitals (except for d(z^2) are _represented_ as four sno-cones, all in the same plane and with their cups pointing at the center (like the blade of a fan). Notice that there is a progression here, as we go from s to p to d-orbitals we go from 0 to 1 to 2 nodal planes (a nodal plane is a plane that can be placed between two -or more - of the balloons without touching any of them). The next step, f-orbitals, will have 3 nodal planes. I will attempt to describe what ONE of them might look like -- there are a total of 7 and will not all look alike (notice the d-orbitals don't all look alike!)

Now to describe what ONE of the f-orbitals might look like. Remember, it has to have 3 nodal planes. Let's just use the x-y, x-z, and y-z planes of cartesian coordinate systems. If each plane were a sheet of plastic it would divide space up into 8 octants (ask a geometry teacher if you cannot "see" this). Now, place a sno-cone in each octant with the point toward the origin. Use 4 red sno-cones and 4 blue-sno-cones and make sure that you alternate red and blue when going from one octant to its neighboring octant (i.e., when crossing a single sheet of plastic). The colors of the sno-cones represent the sign of the wavefunction in that region of space, either positive or negative (which you want to call positive and where you put the first one is completely arbitrary). Remeber, the signs do NOT represent an electrostatic charge -- electrons are always negatively charged! The sign is ONLY the sign of the function used to mathematically represent the magnitude of the electron's wave function in that region of space. Also, you should be aware that one reason more people aren't concerned about the f-orbitals is that they aren't important in most chemical bonds.

Hope this helps!
Greg

Good news! I just found pictures for f-orbitals in "Quanta: A Handbook of Concepts, 2nd Ed.", pg 119. The orbital I described is the f(xyz) orbital.



Click here to return to the Chemistry Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (help@newton.dep.anl.gov), or at Argonne's Educational Programs

NEWTON AND ASK A SCIENTIST
Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory