Now that we're closing in on Christmas, it might be time to do some arts and crafts. Leave the popcorn stringing to other people and pull out copper wire and some nice silver nitrate, so you can make a sparkling silver crystal Christmas tree.
Silver nitrate is a fairly simple molecule. One silver atom is attached to a grouping of one nitrogen atom and three oxygen atoms. This grouping forms a kind of ninja-throwing-star shape. A solution of silver nitrate is usually clear and fairly stable — until you put copper inside it. Copper is a grabby atom, and will yank other atoms, like oxygen, away from molecules. As soon as copper gets close to silver nitrate, it goes to work, grabbing that throwing star of nitrogen and oxygen off the silver atom. The silver, left alone and forlorn, clings to its kin, forming crystals on the surface of the copper. Meanwhile, the newly-formed copper nitrate (yes, copper took its new spouse's last name), swims around in the solution. Because copper nitrate is blue, it stains the water.
How does this spread holiday joy? If you get copper wire and form it into a "tree" shape, then leave it in the silver nitrate solution (which you can get from the more hardcore craft supply stores), it slowly gets covered in silver crystals. After a couple of days you'll "grow" a sparkling Christmas tree. One warning — the solution is turning blue because it is filling with copper atoms, eating away at the wire. If the wire is too thin, the whole thing will collapse, leaving you with a pile of silver rubble. Be sure to get thicker wire to keep your tree upstanding.
Image: Alchemist HP.