Would the gas form Uranium or any other heavy atom be more dense than the liquid form of hydrogen?
The densest known gas is tungsten hexafluoride, at 1.3 g/l. The least dense liquid is probably some form of alcohol which comes in at ~.78 g/cc (780 g/l), so I'm going to have to say no. These figures are for STP; other temperature and pressure ranges may differ.
Liquid hydrogen is about 71 grams per liter. Xenon gas is 5.894 grams per liter at STP (I think). Radon is about 9.73 grams per liter.
I am a little puzzled by the numbers for gas density. Gas is compressible, so the density would increase under pressure. Also I have a recollection (I was exposed to this a long time ago so my memory may be faulty) that at high temperture there is no sharp divide between liquid and gas, so that gas could be compressed to a much higher density.
That's why I specified that the values were given for STP (standard temperature and pressure). Liquid hydrogen doesn't count unless what you're comparing it to is at the same temperature. Otherwise, you're comparing apples to earthworms.
I feel like if there were we would have all seen the youtube video.
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