Not clear where that's coming from, that site lists the bond length for HeHe as 300pm but for HH it's around 75 which would make Hydrogen ~1/4 the size of heliu

Not clear where that's coming from, that site lists the bond length for HeHe as 300pm but for HH it's around 75 which would make Hydrogen ~1/4 the size of helium. On the scale of individual atoms I don't remember enough about my chemistry and physics courses to recall whether there's supposed to be much physical difference between the "size" of the region where the first 2 electrons are between different atoms, nor do I know if that's being conceptualized as orbits, shells, abstract concepts of energy levels of something even weirder these days.