Watch ions bounce around your screen!

An attractive wallpaper featuring ions (as well as neutral "noble gases") from chemistry which bounce around the screen and interact. It is based on chemistry, but you certainly do not need to know chemistry to appreciate it.

There are several options which be used via the wallpaper settings:

- Color scheme

- Up to four different particle types

- Number of particles of each type

- Bonding - if turned on the ions will stick together and form 2-d crystal structures and if turned off they will zoom around attracting and repelling but not slowing down.

The ions used are based on real-life chemistry, but the realism is pretty limited for the sake of simplicity. For those who are interested, below I've listed some of the ways this is like and unlike real chemistry.

Ways this is realistic and like real-life chemistry:

- Mass, charge, and radii are based on their actual relative proportions

- Positive and negative charges where likes repel and opposites attract (uses the Coulomb equation)

- Van der Waals interactions and simulated repulsion due to the Pauli exclusion principle (handled with the Lennard-Jones potential equation)

- With bonding mode on, crystal structures often resemble 2-d versions of their 3-d counterparts

Ways this is unrealistic and very much unlike real-life chemistry:

- Uses classical physics, while in real life quantum effects are very important in atomic-level interactions

- Unrealistic treatment of reaction energy

- Constants in the equations used are "fudged" to make it look good rather than

- With bonding mode off, nothing like chemical reactions actually happens

- No covalent bonds (yet)

- Real atoms and ions are not circles or balls, but have much more complex orbital geometries