Note to the reader: The translator is having a problem showing
the Greek letter psi for the wave function; it translates as a
capitol Y. With a little luck you should be able to tell from
the context. Good luck.
All exercises should be completed on this sheet as the software
is being used.
Introduction: To familiarize yourself with the software first double-click on the Atomic Orbitals folder to open it, then open the software by double-clicking on the software icon within this folder. When the title screen comes up press command D (apple key & D) on the keyboard to start the instructional demonstration movie. After viewing it, start the program itself by clicking sequentially on the two title screens. This will bring you to the Introductory screen of the program. Listen to the narrator (you may stop the narration at any time by clicking the mouse, and restart it by clicking on the speaker icon).
To begin your exploration of atomic orbitals go to the "s" screen by clicking on the appropriate map icon. Here you will explore the simplest family of atomic orbitals. When the narration finishes, click on the book icon for text regarding the screen. Note that there is new text for each screen in the program.
Exercises:
1. According to the text, a 2s orbital may be described as:
2. Click on the bolded term "probability-density." What
is the definition of this term in the glossary? (Click on Max
or Irwin to see what they have to say about it.) When you are
finished click on Done, then close the book by clicking on its
icon.
Now go to the 1s orbital screen by clicking on its icon on the
map. Next, rotate the orbital by clicking on the button on the
new control panel on this screen (labeled 1s). Note that you may
chose the axis of rotation by clicking on the axis button on this
panel.
Exercises:
3. Describe this orbital.
Next click on the next to right-hand button on the map.
Exercises:
4. How many nodes are shown for this orbital?
Now click on the center button on the bottom of the map. Open
the book and read about how to use this screen.
Exercises:
5.a. Set the arrows at a radial distance of 0 by click-dragging
the arrows, or just click on the location you want them to jump
to. Where does the arrow appear on the "textbook style"
2-D Y2 plot? What is the relative probability at this
point?
b. What is the radius of the spherical surface having a relative
probability of finding an electron equal to 0.10?
6.What does the orange surface in the main-window represent?
Try the other two buttons.
Now click on the 3s button on the map. Again begin by looking
at the rotation movie for this orbital. First click on the far
right-hand button on the bottom of the map, this will access the
rotation screen. Next, rotate the orbital by clicking on the button
on the new control panel on this screen. Then look at the nodes
screen (the adjacent button). Note that you can toggle between
the nodes by clicking on them on the screen.
Exercises:
7.What are the radial distances for the two nodes? How did you
find these values? (What is the "bug" in the software
for the nodes on this screen?)
8.How does the 1s orbital compare in size to the 3s orbital?
Click on the cross-section (X-S) button to call-up this screen,
and click on the arrow at the left end of the new control bar.
Exercises:
9. How may nodes are visible? Describe their appearances.
Now go to the 50/90 screen by clicking on its button. Read the
text.
Exercises:
10. What do the surfaces shown on this screen represent? What
is the particular significance of the 90% surface?
Go to the 3px orbital by first clicking on the p button (listen
to the narration, and if you like, read the text), then the 3p
button, and finally, the 3px button. Then, starting with the 50/90
button, explore the five screens.
Exercises:
11. How many nodes are evident in the representations of this
orbital? How many nodes does it have in total?
12. Describe the angular node (where is it located?).
13. In which representations of the orbital are the nodes particularly
noticeable? How do they appear?
You will notice that a new button appears on the control panel
of the rotation screen. Click on it if you havenÕt already.
Exercises:
14. What does this movie demonstrate about the p-orbital set?
Now click on the 3py button and go to the cross-section (X-S)
screen. Take a cross-section.
Exercises:
15. What do you see? Is something wrong? Try the Y2
button. What do you see now? What is the highest probability for
finding an electron on this screen?
Look at the movies for this orbital, then go to the 3pz orbital
and look at the cross-section and rotation screens.
Exercises:
16.Try the Y2 button. What do you see now? What is
the highest probability for finding an electron on this screen?
How does the image compare to those for the 3px and 3py orbitals?
Now click on the d and then the 4-6's buttons, and study the images.
Exercises:
17.How many nodes are evident for the various d orbitals?
How many lobes? How many nodes are evident for the various f
orbitals? How many lobes?
18.Are the numbers of lobes consistent with the numbers of nodes
for the d and f orbitals? Which is more fundamental?
Finally, when you are on the 4-6's screen, click on the s-f's
button. Read the text.
Exercises:
19.At a given value of n how does the size of an f
orbital compare to an s orbital? a p orbital? a
d orbital?
20. Estimate the number of 1s orbital radii in one 6s orbital
radius.
Click on the various icons for the orbitals with n=6, rotate
them and note the complex nodal structures evident in these orbitals.
Compare one or more of them with the corresponding orbitals at
lower energy levels. Note that within the software you can compare
all of the energy levels up to n=6 for one orbital orientation
in each set.
This completes our guided exploration of the atomic orbitals of
hydrogen. However, you may want to further explore the hydrogenic
orbitals, including 3d and 4f orbital sets on your
own. Some of the rotation movies for the f's are particularly
spectacular and, in our opinion, quite beautiful! Enjoy.
Updated: 18 February 1997
© R A Paselk
Last modified 4 June 2001