The ratio of hydrogen to oxygen in water is 1:8. One unit of hydrogen is added to one unit of oxygen that weighs 8 times as much. In the previous post I said that the ratio of 1:8 in water vapour was not relevant. I think I might have been mistaken. Maybe the atomic number of water is rightly 9, and not 17. As a gas, oxygen weighs 16 times more than hydrogen. If you were to add one volume of hydrogen to one volume of oxygen it would give you a combined atomic weight of 17.
If the hydrogen atom does shrink when it reacts with oxygen to make water vapour, then it's likely that the atom shall become more dense. The same amount of energy which occupied 2 volumes now occupies only one volume. This one volume of hydrogen, which has a density twice that of a hydrogen atom in gas, is now part of a water molecule with one volume of oxygen which now weighs 8 times more.
It remains that one volume of reduced hydrogen gas is in a reaction with one volume of oxygen gas to produce two volumes of water vapour. In this reaction the ratio is 1:8. The atomic weight of water vapour should therefore come to a grand total of 9. If the steam was cooled and condensed into water, it would occupy a volume some 1700 times smaller than the steam.
I would have to summise though that in the reaction to make water we have one volume of hydrogen gas and one volume of oxygen gas. The hydrogen starts out as two volumes, but as it burns, it is reduced, or compressed, into one volume. Therefore, in terms of volume, water is 50% hydrogen, and 50% oxygen. That's my yin to your yang, man.
I just don't think atomic weights work. This ratio of 1:8 would mean that there is 8 times more oxygen than hydrogen in water vapour. I don't think this is true at all. I think water is made up equally with one half hydrogen and one half oxygen. I'm starting to get a feel for relationships in other compounds which are based in atomic weight ratios. I get the sense that none of them stand up in terms of volume. I could be wrong. I can see this theory is going to need a lot more work. I probably need more sleep. Mmmmm....sleeep.