There are many high-tech depictions of atomic orbitals available in text books and online. However, nothing beats actual models you can hold in your hands. Below we describe how to make physical models of atomic orbitals using craft store supplies. We think they are an eggscellent approximation of three-dimensional boundary surface diagrams. We suggest building a set of p orbitals as described in another link before you tackle this project.
Materials
Eighteen styrofoam eggs (3 1/16 in. x 2 5/16 in.)
A square or disk of styrofoam (3 in. across and 1 in. thick)
Sixteen lengths of 1/8 in. dowel rods (one 16 in., seven 7 in, two 5 in., six 3 in.)
One 16 in. length of 1x4 board and one 12 in. length of 1x4 board
Kite string, wood glue, hot glue gun, sandpaper
Drill and 1/8 in. bit
Once you have sanded the 16-inch 1x4, draw a faint pencil line down the center of the board. On the line drill a hole at the midpoint 8 inches from the end. Drill two more holes 3 inches from each end. Erase the pencil line. Glue a 7-inch dowel in each hole using wood glue. Do your best to get the dowels vertical. These vertical dowels represent z-axes.
Make a small pencil mark 2 7/8 inches from the board on each vertical stick. Use kite string to tie the 16-in. dowel across the vertical sticks at the marks. Center the horizontal dowel so it doesn't extend past either end of the base. Add a drop or three of wood glue where the dowels intersect. (See photo.) Once the glue has dried, snip off the excess string. This horizontal dowel represents the x-axis.
Place a ruler on the board just inside and perpendicular to one of the outer z-axis dowels. Make a pencil mark 1/4 inch from each edge. Drill a hole, slighty toward the middle of the board, next to each mark. Insert a 3-inch dowel in each hole. Place one of the 5-inch dowels on top of the two 3-inch dowels and next to the intersection of the z- and x-axes. Adjust the height of the support dowels and the position of the 5-inch dowel until the 5-inch dowel is centered and perpendicular to the x- and z-axes. Carefully remove the 5-inch y-axis dowel, apply a drop of glue to the tops of the support dowels, and replace the y-axis. Tie kite string around the juncture of the axes and apply a drop or two of wood glue. Later snip off the excess string.
At the other end of the board, add a glob of hot glue on the insides of two adjacent dowels about 1 inch from the juncture. Insert an egg, small end toward the center, and hold it against the dowels and the board until the glue hardens a little. This is the first lobe of the dxz orbital.
Glue three more eggs in a similar fashion. Do your best to get them all centered and at right angles. This completes the dxz orbital.
Tie a length of kite string at the mid-point of the other 5-inch dowel. Tie the dowel to the juncture of the middle axes making sure it is under the horizontal 16-inch dowel. Hold the dowel perpendicular to the two axes and prop two eggs under it to hold it in place.
Fine tune the position of the eggs and dowel until this y-axis is level and at right angles to the other two axes. Apply wood glue at the juncture of the three dowels. (Do not glue the eggs yet.) Allow the wood glue to dry completely.
Once the wood glue is dry, hot glue four eggs between the axes in the dyz plane. Again, be sure to point the small ends toward the middle and position the eggs centered in the yz plane. This completes the dyz orbital.
Now hot glue four eggs in the xy plane of the last set of axes. As before, point the small ends toward the middle and center the eggs between the x and y dowels. This completes the dxy orbital.
If you like, label the orbitals. Your styrofoam egg dxy, dyz and dxz orbitals are ready for display.
Lightly pencil a center line down the length of the 12-inch board. Drill four vertical holes 2 inches, 6 inches, 8 inches, and 10 inches from one end.
On a line perpendicular to the center line, drill two more holes 1 1/4 inches from the 8-inch hole.
On the 1-in. thick piece of styrofoam, use a compass to draw a 1-in. circle surrounded by a 3-in. circle. Carefully cut this wheel-shaped donut out with a sharp knife.
Round the outer edges with sand paper. Take your time. This is the most tedious step. You should be able to shape a uniform donut about 3-in. across and 1-in. thick.
Sharpen one end of a 7 in. dowel and carefully push it lengthwise through the center of an egg. (Try inserting it about 1/4 inch and then rotate the dowel between your thumb and fingers. If the egg wobbles, the stick isn't centered.
Adjust the placement of the stick until the egg doesn't wobble much.) Impale a second egg in a similar manner. Be sure the small ends of the eggs point toward the center of the stick. These two eggs form two of the lobes of the dz2 orbital.
Hold the stick with two eggs with the sharp end pointed down. Gently slide the top egg off the stick.
Adjust the bottom egg until the big end is about 1/2 in. above the sharp end of the stick. Add some wood glue to the hole at the 2-inch spot and glue the stick and egg there.
Add a little glue around the pointed end of the bottom lobe. Carefully place the donut over the stick until it rests on the bottom lobe. Be sure it is level.
Add a little glue on the inner edge of the donut and gently slide the top egg back on the stick with the small end down.
The dz2 orbital is complete.
Insert a 7 in. dowel into two eggs with their small ends toward the center. Leave about 1/2 inch of space. Repeat this process with the last two eggs.
Fine tune the distance between the lobes on each stick and place them perpendicular to each other on the table. Make sure the dowels touch and gently push the eggs toward the center to help hold them all in place. Apply a drop or two of glue where the eggs touch. When dry, apply glue to the other side.
Glue the last 7-in. dowel in the 8 inch hole. Sharpen one end of the 3-in. dowels and glue them, sharp end up, in the four remaining holes.
Get the dowels as vertical as possible.
After the glue has dried, lower the dx2-y2 orbital on the pegs with the 7-in. dowel between the four lobes.
Center the lobes above the pointed pegs and point the orbital along the x- and y-axes. While applying pressure on all four lobes, carefully push the eggs onto the sharp
pegs until they are level with the donut lobe of the dz2 orbital.
Add labels and your dz2 and dx2-y2 orbitals are complete.
©2010 W.C. Deese. All Rights Reserved.