THE HYDROGEN PUZZLE

摘要

We often see hydrogen atop group 1 although hydrogen is very different from the other elements in the column.Unlike group l elements,hydrogen is not a metal,it's a gas at room temperature,and it bonds covalently most of the time.Group 1 elements are metals,solid at room temperature,and form only ionic bonds.So,why is hydrogen grouped with these metals?Today,we know that hydrogen has a single electron in its electron shell,defined as a set of electrons with similar energies in an atom.This shell contains one subshell,which consists of one orbital.An orbital is a region of high probability of finding an electron.Each orbital can hold up to two electrons.