At the molecular level symmetric patterns constantly show up.Even a single water molecule shows symmetry.

Kinemage 1, which will appear on screen when lesson 4 is clicked on, shows a single water molecule.

**What types of atoms is water composed of?____
**What is the chemical formula?_________

Click on the ends to demonstrate the location of the hydrogens. The middle will show the oxygen.

**Measure the distances from oxygen to either hydrogen. What value do you get?____________

**Is the distance from either hydrogen to the oxygen the same?__
**What type of symmetry does this represent?_______

It is important to note that the units for the distance measurements are all in "Angstroms". An Angstrom is 1/10,000,000,000 of a meter. Angstroms are always used when we measuring at the atomic level. Can you give a reason why?

Find the angle represented for the water molecule on the screen.
Is it acute or obtuse?_____ What is the measure?_______

Click off the water molecule, and click on the methane molecule. A methane molecule will appear. We have seen this shape before.

**What geometric shape do you think the methane will fit into?___________ Why?___________________

Click on the tetrahedron box at the right side to demonstrate this. Leaving the tetrahedron on. To find out what methane is composed clicking on each atom. Remember you must click at the ends of the
lines.

**Methane is composed of _____________.
**The chemical formula for methane would be _________.

**Measure the distance from carbon to each hydrogen?_________
**Measure the angles that form the tetrahedron?___

_________________________________________________________________________________________