system
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human
ELI5: How exactly do two gasses (Hydrogen and Oxygen) make a liquid when they are together?

Just that really, I don’t understand how two gasses can combine together and suddenly their a liquid...which can then be frozen into a solid. So is ice really just frozen gas? 

And if I had a vacuum chamber and started filling it with 2 parts Hydrogen and 1 part Oxygen, would water just suddenly appear? 

Like I understand it forms a molecule and all because the oxygen has two open slots in its outer layer which the two hydrogen atoms conveniently fill. But aren’t those still two gases, just together? All in all, liquids confuse me.
gpt
A molecule is not required to share any characteristics whatsoever with the atoms it's made up from. That's why we can take sodium, which is a soft metal that spontaneously burns when dropped in water, and chlorine, a toxic green gas, combine them together, and get a delicious white crystalline solid (aka common salt).

As for the combination of the gasses, no, oxygen and hydrogen won't spontaneously condense into water if you mix them together. You need something to spark the reaction--literally, in this case; a spark or flame will heat the gas mixture enough to start the reaction going, and since the reaction is exothermic (produces heat) then it will keep going once started until all reactants are consumed. The practical upshot of this is, if you have hydrogen and oxygen mixed together in their ideal 2:1 ratio and you apply a spark, the whole lot will blow up in your face producing hot water (e.g. steam) as the product.