3–D Helium Molecule Tutorial Alice Project Duke University Professor Susan H. Rodger Gaetjens Lezin June 2008

In this tutorial, we will be building a 3–D electron cloud model of a helium atom. We will also add a billboard that will serve as a legend. Use paint or your favorite drawing tool to do this step. To begin, open a new Alice world and choose the sand template. Introduction and Setup

Select the local gallery and scroll over to the shapes folder. Hint: If you cannot find the SphereHighPoly Object, click search gallery and type SphereHighPoly. Building the Nucleus (Adding Objects) Click the green add objects button. Select the object SphereHighPoly, add four of these objects into your world. Then click Done.

This is what your world should look like. Now line them up in a row by clicking on them and moving them left or right. They should be touching and half way sunk into the ground. Notice the four new items on the object tree Click and hold on the shape to drag it Building the Nucleus (Adding Objects)

Look at the object tree and right click on the SpereHighPoly object and select rename. Name it ProtonA. Now select the properties tab, click next to color, and change it to red. Building the Nucleus (Renaming) This is how your screen should look after renaming and changing the color of one sphere. Your spheres may be in a different order. That is fine.

We want to name and set the second shape, SphereHighPoly2, the same way we did the first one. To do this, right click on SphereHighPoly2, then rename it NeutronA. Then click the properties tab and set the color to yellow. Building the Nucleus (Renaming) This is how your world should look after renaming and changing the color of two spheres.

We are going to repeat the instructions on the last slide for the third shape we added, SphereHighPoly3. Rename this object ProtonB. Set its color to red. Building the Nucleus (Renaming)

Now repeat the same steps for the last sphere in the object tree. Rename it NeutronB. Set its color to Yellow. Building the Nucleus (Renaming)

Now we want to resize the particles that make up the nucleus. There are a few ways to resize items in Alice. We will use methods to reduce ambiguity. Building the Nucleus (Resizing) Right click on ProtonA. Click on Methods. Select resize. Select other and type.5, then click Okay.

We want to make all the protons and neutrons the same size. So repeat the resize instructions on the last slide for NeutronA, ProtonB, and NeutronB. The next step is positioning the particles. All the nucleus particles resized to.5 units Building the Nucleus (Resizing)

Lets start off with the leftmost particle. This should be ProtonB. If it is not, reorder your line so you have in order from left to right: ProtonB, NeutronA, ProtonA, NeutronB Once the particles have been resized it is easy to rearrange the order. Just click an object, hold, and drag it to where you want it. Hint: Click on an object and its name will be highlighted in the object tree Building the Nucleus (Positioning)

Once you have them lined up, we will move them. Right click on ProtonB and select Methods.Select Move, then Up. Choose Other, type 2 and click Okay. Building the Nucleus (Positioning)

Now lets move the right-most particle, NeutronB, up 2 meters. Follow the same instructions from the last slide. NeutronB has moved up 2 meters The next step is to put the 4 atoms together. We will use methods to adjust their positions. Building the Nucleus (Positioning)

Right click on NeutronB and select methods. Then select move toward. Select 2 meters, then select ProtonB. The particles should look like this when you are done. Building the Nucleus (Positioning)

Now we will move NeutronA up 1.5 meters. Click on NeutronA then select methods. Click Move, then Up. Select other from the dropdown menu. Enter 1.5 then click Okay. If they are not touching, click on it and move it until they are touching like the picture shown. Building the Nucleus (Positioning)

Now we need to move the last particle, ProtonA, up. Click on ProtonA and select methods, then move. Select up, then select 1.5. Next we want to move ProtonA towards NeutronA a distance of ½ meter. Building the Nucleus (Positioning)

Right Click on ProtonA then choose methods. Select move toward. Choose ½ meter, then NeutronA. Note: If they are not touching click on it and move it so they are touching like the picture shows. Building the Nucleus (Positioning)

The last particle we need to position is ProtonB. Right click on ProtonB and choose move toward. Select 3/4 meter then choose Neutron B. The world doesn’t look exactly perfect after ProtonB is moved. Use the move objects freely tool on the Add Object screen to get it exactly right. Building the Nucleus (Positioning)

Add another sphereHighPoly object to your world. It is located under Local Gallery, then shapes. You should already be here. If you can’t find it search for sphereHighPoly. Electron Cloud (Creation)

Click on the object you just added and resize it by 2. Then use its move method to move it up 2 meters. Now change the opacity to 30% by clicking on the properties tab, then clicking next to opacity and selecting 30%. Electron Cloud (Creation)

Use the up and down tool on the Add Object screen and move the electron cloud down a little by clicking on it and holding it until the nucleus is in the center. Electron Cloud (Positioning)

Now select the move objects freely tool to move the electron cloud a little to the left. Click, hold and drag the Electron cloud a little to the left. Electron Cloud (Positioning)

With the electron cloud in place, we want to set all the particles inside the nucleus as a vehicle to the electron cloud. Before we do this, lets rename the object SphereHighPoly in the object tree to ElectronCloud. Electron Cloud (Renaming)

Click on ProtonA on the object tree. In the properties tab click next to vehicle and select ElectronCloud. Repeat this step for: NeutronA ProtonB NeutronB Electron Cloud (Properties)

We will add 2 electrons to the world. First navigate to shapes in the local gallery. Click on SphereHighPoly and add it to the world, just like you have done before. Right click on it in the world, select methods, then resize, then choose other and type.5. On the properties tab, click next to color and select green. Electron (Creation)

Now lets give a name to our electron. Like you have done before, go to the object tree and right click on SphereHighPoly and rename it Electron1. Electron (Renaming)

Eventually we will make the electrons revolve around the electron cloud. For this to work right, we have to position the electrons in the proper place. I will try and use methods to position the electron, but you can also use the Move Objects Freely button. Click Add Object to get these options. Electron (Positioning)

Right click Electron1 on the object tree and select methods, move, then up, then other. Type 4 meters and click Okay. The world should look like this once you have moved Electron1 up 4 meters. Hint: Click and move electron1 to resemble the picture. Electron (Positioning)

Go back into Add Objects then to Local Gallery. Go into the Shapes folder and add another sphereHighPoly object. Change the color to green. Resize it to.5 meter and rename it Electron2. Electron (Creation)

We want to set the vehicle properties of Electron1 and Electron2 to the Electron Cloud. So click on Electron1 on the object tree. In the details panel, click on the properties tab and click next to vehicle. From the drop down menu select ElectronCloud. Repeat all of the previous steps on this slide for Electron2. Electron (Properties)

Now all the properties are set up. We just need to position the entire model so that it is in the middle of out screen. To do this use the Move Object Freely button. Model (Positioning) Click on the ElectronCloud in the world window and move it backwards. Next click on the Move Objects Up and Down button and move it up a little bit. Notice all the sub atomic particles move with the electron cloud.

Click Done to go back to the initial Alice window. Next we will code the model so that the electrons revolve around the electron cloud together. To do this, we will put the electrons in a list so it is easier to move them together. Coding (Setup)

First click on the world tab on the object tree. Click on the properties tab, then click on create new variable. Coding (List) A window will pop up. Type Electrons in the name box. Click the radio button next to Objects. Click the check box that says make a list. Add two new items to the list by clicking on new item twice.

Click next to and select Electron1. Click next to the second and choose Electron2. Then click OK. Coding (List)

Now drag a For all together statement into the editor window. From the drop down menu select expressions then World. Electrons. Coding Then click on Electron1 on the Object Tree. Then click on methods in the details panel.

Scroll down to the statement that says turn at speed. Drag and drop this into the For all together statement. From the drop down menu select forward. Then select.25 revolutions per second. Coding

Now lets drag the tab that says item_from_Electrons from the For all world.Electrons statement. Drop it over Electron1 in the turn at speed statement. At the end of this statement click the triangle facing down next to more. Select asSeenBy, then ElectronCloud. Coding

Click the triangle next to more again and select duration. Choose other. Put in a large number like 1,000,000,000. Click Okay. Hint: Press play, You may need to reposition the electrons if they don’t revolve properly Coding

You may want to move Electron2 a little further away from the ElectronCloud. Simply use the Move Objects Freely button to do this. Also you may want to add a billboard that is a legend of what each piece of your model represents. For example, I used paint to create this legend. Save the Picture as any one of the following; JPEG,PNG,BITMAP,GIF. Alice will accept all of these formats. Finish Touches

To add this billboard to my world I will click on file then choose Make a Billboard. Then I go to the folder where the picture I created using paint is located, click on it, and then hit Import. Note: Place the billboard where you want it. Finish Touches (Billboard)

I hope you enjoyed my tutorial. Have fun with Alice!! :-D Final Image