Workout: Chemical bonding

Read

Read the web page Chemical bonding .

Launch

Go to the PhET simulation Atomic Interactions to perform a few tasks.

Set up

Go to the hamburger (three stacked lines) at the lower right, choose "Options", and select Projector Mode.

Toggle “Custom Interaction” at the bottom of the list of possible atom-atom interaction models.

Shift “Atom Diameter (σ)” to the middle of the range, and “Interaction Strength (ε)” three-quarters of the distance from the Weak setting to the Strong setting. Click the + sign on the forces window and select to show the Total Force arrow. These settings models two interacting hydrogen atoms. Grab the right atom with your mouse and one it some distance away from the other atom.

Your screen should look something like this.

Answer these questions

A. The Hydrogen Molecule, H₂

1. Separate the “moving atom” half way up the potential energy curve. Release and observe the behavior of the moving atom with respect to the “pinned atom”. What do you see?
2. Pause the simulation and move the “moving atom” closer to the “pinned atom”. What happens to the potential energy of the H2 molecule? To the force on each of the atoms?
3. From a high potential energy position of the molecule with the two atoms very close, release the “moving atom”. What happens?
4. Drag the “moving atom” to the right, increasing the distance between the atoms. What happens?
5. Many molecular model systems use perforated Styrofoam, wooden, or plastic balls to represent atoms and wooden sticks to connect the atom models. Based on your observation on the simulation, rather than describing a chemical bond as rigid as a wooden stick, interacting atoms behave as:…
6. Based on the behavior of the interacting atoms, how would you define “bond length”?
7. How would you define “bond energy”?
8. How would you define "binding energy"?

Dave Buehrle Fall, 2016
Joe Redish 2/27/19