If you kids are quite done.
the reason Hydrogen is so reactive is that, like metals, a hydrogen atom needs to gain an electron to complete it's outermost shell. And since that shell is the innermost one possible, it is closest to the nucleus, which is positively charged and thus attracts the negatively charged electrons. the close proximity makes the attraction strong and thus easily fulfilled. This reactivity accounts for it's rarity in a pure form on Earth, but since it's pure form is the lightest gas it has the same difficulty as Helium: it is too light to be effectively held by Earth's gravity and is therefore easily lost into space. What little remains in that form during the journey, anyway. Helium is the second most common element in the universe, but our entire supply comes from reduced alpha particles emitted by alpha decay of radioactive elements inside the Earth. I'll leave someone else to comment on our obscene squandering of this industrially useful commodity.
Actually, Helium atoms are very stable for the same reason that Hydrogen atoms are very reactive: the closest electron shell to the nucleus is filled, thus to form compounds it would have to either share one or both electrons with another atom (expanding their orbits against the electromagnetic force that binds them) or become an ion by losing one or both entirely, which is very difficult. I suppose it could also gain one in the next shell up, but that is not a very tenable state at all. I only know of two Helium compounds. One is Helium Hydride, HeH+, and it is formed when a Tritium atom (Hydrogen-3) in either T2 or HT decays by beta decay into Helium-3 and the molecule remains bound together. It is the strongest known acid (though it is so powerful that it could not be prepared because it would react with the water, though it is possible to calculate what it's aqueous acidity would be). the other compound is HeH2. Both have been identified by mass spectrometry in space, such as the atmospheres of white dwarf stars.
Obviously I've ignored the effects of quantum physics in these explanations.
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Yes, what Phylum said. If we could get a cheap and reliable supply of hydrogen, we'd actually solve our energy issues far sooner than we solve water supply as fuel cells are a useful technology. Right now the only way to get large amounts of hydrogen is to use vast amounts of electricity to split the H2 from the O.
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I'm intrigued by this. Can this sentence not be simplified: "if we had a cheap and reliable source of fuel we could solve our energy issues"? It's not exactly revelatory, is it?
