In this animation the interaction between two water molecules will be shown. Click the mouse to start the animation. The water molecules will move to the center of the animation and pause. Begin answering the questions after the molecules stop moving.

Important do not press the enter key or the Return key while you are answering these questions. Your Browser will interpret either key the same as clicking the mouse on the Submit button. So BE CAREFUL!

Give me some responses to the questions below and I'll give you some extra credit.


Laboratory Section:

1. There are two water molecules shown in the center of the animation, indicate which atom(s) is oxygen and which atom(s) is hydrogen. The two colors of atoms I see are bluish-green and red. (Click the mouse to continue after answering this question to resume the animation.)

Expert's Response:

The larger 'red' atom (circle) is oxygen and the smaller 'blue-green' atom (circle) 'on' the red atom are hydrogen atoms.

2. The next time the animation pauses, indicate the partial charge (positive or negative) on each atom in the two water molecules. Use the numbered atoms to help with labeling. Do not forget which atom is hydrogen and which is oxygen. Anwer Question 3 before resuming the animation.

Expert's Response:

The partial charge on an oxygen atom (#2 and #5) is negative and the partial charge on a hydrogen atom (#1, #3, #4 and #6) is positive.

3. Explain how you arrived as the partial charge assignment you used in Question #2. (Resume the animation after answering this question.)

Expert's Response:

The partial charge on an atom in a molecule depends on the atom's relative electronegativity. Comparing the two atoms sharing a pair of electrons (or more than a pair) the atom with the greater electronegativity will have the partial negative charge and the atom with the smaller electronegativity will have the partial positive charge.

4. Using the numbers identify the atoms likely to participate in the hydrogen-bonding intermolecular attractive force.

Expert's Response:

Hydrogen bonding can occur between a oxygen atom on one molecule, either #2 or #5 and a hydrogen atom on an adjacent molecule. So in the case shown in the animation the hydrogen bond will be formed bewteen the two water molecules, and more specifically between oxygen atom #2 and hydrogen atom #4. Other possible hydrogen bonds could also have formed; i.e., O2 and H6, O5 and H1 or O5 and H3.

5. If there were three molecules of water in the frame where (which atoms) would another hydrogen-bonding interaction form.

Expert's Response:

If a third waer moecule were in the frame than a hydrogen bond could form by either hydrogen atom of the new water molecule interacting with O2 or O5. Also the possiblity exists that the hydrogen atoms H1, H3, H4 or H6 could interact with the oxygen atom of the new water molecule.

6. Is there anything about this animation that you feel you do not understand? List your concerns/questions.