Extensions:
Extend this History Note: Learning That Water is made of Hydrogen and Oxygen. Scientists didn't always know what atoms made up water. (You might ask students, "Do you?") In 1781, Cavendish, an English physicist, prepared water by exploding a mixture of oxygen (O2) and hydrogen (H2). Cavendish: O2 + H2 ¦ H2OA year later, Lavoisier, a French chemist who was executed in the French Revolution, decomposed steam by passing it over iron. He showed that water can be decomposed to hydrogen and oxygen. Lavoisier: H2O ¦ O2 + H2 Read more about Cavendish, the man of few words but many experiments. http://mattson.creighton.edu/History_Gas_Chemistry/Cavendish.html Read more about Lavoisier, the French martyr to the revolution. http://scienceworld.wolfram.com/biography/Lavoisier.html
Measuring density: Freeze the simulation and count how many hydrogen bonds are formed and measure the density of the liquid. There should be almost two bonds per molecule and the density should remain constant wherever there is water, independent of the container, providing the container is large enough.
What happens when the temperature drops? It should be clear that polar molecules make harder crystals. One of the ice rules: Each water molecule is oriented so that its two hydrogen atoms are directed approximately toward two of the four oxygen atoms which surround it tetrahedrally, forming hydrogen bonds.
The appearance of water in the universe http://witcombe.sbc.edu/water/physicsuniverse.html
Read about Hydrogen
Bonds [replace with search words]
http://www.aip.org/physnews/preview/1999/h-bond/h-bond.htm
http://mccoy.lib.siu.edu/projects/chem140a/CH06ED/sld024.htm
(plus next two slides)
http://mdp2.phys.ucl.ac.uk/Talks/Ice/Ice.html
http://www.biology.arizona.edu/biochemistry/tutorials/chemistry/page3.html
http://www.sbu.ac.uk/water/hbond.html
http://www.aip.org/physnews/preview/1999/h-bond/h-bond.htm
http://www.sbu.ac.uk/water/anmlies.html
Additional Resources:[replace
with search words]
Water:
its structure and importance - Martin Chaplin
http://www.sbu.ac.uk/water/
http://www.sbu.ac.uk/water/molecule.html