Metallization pressure is different for ten different elements, one of which is hydrogen (the symbol H and atomic number 1) with a p, Mbar of close to 4.
hydrogen 3.9 The bar is a metric unit of pressure, but not part of the International System of Units (SI). Hydrogen is the chemical element with the symbol H and atomic number 1. helium 329 boron 1.6 carbon 11 nitrogen >> 5 oxygen 0.96 neon 2084 silicon 0.12 phosphorus 0.048 sulfur 0.83 Every material is predicted to turn into a metal if the pressure is high enough, and temperature low enough. 
