Things nobody knew about hydrogen....
https://www.nature.com/articles/nature02910
,,,,,,,,,,,,,,,,,at high (but experimentally accessible) pressures, compressed hydrogen will adopt a liquid state, even at low temperatures. In reaching this phase, hydrogen is also projected to pass through an insulator-to-metal transition. This raises the possibility of new state of matter: a near ground-state liquid metal, and its ordered states in the quantum domain.,,,,,,,,,,,,,