1, because it has an atomic number of one, meaning it has 1 proton & 1 electron. It takes 2 electrons to fill the first electron shell, but hydrogen only has 1. So it remains at the 1st shell.
3 i thinkno one, hydrogen is the lightest element on the periodic table it is also very flamable ever heard of the dirigible that contained hydrogen and blew up? killed many people so now everyone...