[gluedudeguru]

If water freezes (many molecules) it expands the colder it gets.  Would just 1 or 2 molecules of water expand when frozen?

Also, how many chemical words or ideas or anything to do with the chemical world start with the letter J?  Iv wondered this for years.  Not including any names, unless itself is the chemical reference

1) Joule
2)
3)

[cpncoop]

Water expands because it forms a hydrogen bonded network that gives a well ordered lattice that is less dense than water (hence it floats).  The individual molecules (I believe) don't expand per se, although bond lengths and angles do slightly change due to H-bonding, temperature, etc.... In order to expand, you need to form a crystal, which takes at least the number of water molecules in the unit cell of the crystal structure of ice.

As for the J question, a few off the top of my head:

J (the coupling constant)
Jablonski diagram (excited state molecules)
Jone's oxidation

that's about all I can think of, good question....

[cpncoop]

Jahn-Teller distortion is another J

[stewie griffin]

Jacobsen epoxidation