Most of the elements in the periodic table are metals of some kind. These include Alkali metals (except hydrogen), Alkaline Earth metals (Group 2), Transition metals (Groups 3-12), Poor metals and Metalloids (Groups 13-16), over 80% of the elements. In the traditional Periodic Table shown below, the blank white boxes include all these metallic elements.

There are three classes of non-metallic elements, Noble gases (Group 18 - blue), Halogens (Group 17 - yellow) and Nonmetals (green). Most of them are gases and they occupy the upper right-hand corner of the Periodic Table except, of course, for hydrogen.

The main characteristic (rule) of Group 1 (the left column) is that all the elements in this group have a single electron in the outer shell of their atoms. Since this is also true of hydrogen, technically, hydrogen can be 'legally' placed where it is.

But the periodic table is also supposed to help organize some of the properties of the elements it displays according to their position in the table. The only property that hydrogen has in common with the alkali metals (the rest of Group 1), besides having a single electron in its outer shell is that they all combine very easily with halogens to form various compounds (more about this below).

The halogens (yellow) are Group 17 and a 'general rule' for that column is that one electron is missing from the outer shell of their atoms. Halogens are chemically very active (easily bond with other elements) because of the single missing electron in the outer shell of their atoms.

In general, the lightest halogen (flourine) is the most chemically active and they become less active as they get heavier. Halogens have a special affinity for bonding with the Alkali (Group 1) metals because each of those has a single electron in its outer shell. The atoms fit together snugly like puzzle pieces.

The two lightest halogens (flourine and chlorine) are both gases and both are flammable, like hydrogen. In fact, these three gases are the ONLY flammable gaseous elements. The next halogen is Bromine which is the only non-metallic element that is a liquid at room temperature.

Hydrogen is a legal member of BOTH groups (1 and 17) since it has both one electron in its outer shell AND one electron missing from its outer shell (a very unique combination). Hydrogen bonds even MORE readily with all the other elements in both groups (alkali metals and halogens). Hydrogen and flourine are the most reactive, being explosive when mixed.

I believe hydrogen is best described as a halogen. Hydrogen fits very nicely at the top of Group 17 without even changing any rules for the periodic table!

The 'number of missing electrons in the outer shell' rule should always take precedence over the 'number of electrons present in the outer shell' rule. Otherwise, one could also argue that helium belongs in group 2 (alkali earth metals) since it has two electrons in its outer shell, but that makes about as much sense as classifying hydrogen as an alkali metal (group 1).

Hydrogen displays so many of the properties of the halogen group (17) that I find it hard to believe that nobody has noticed this before. My new and improved Periodic Table even LOOKS more elegant than the the current traditional one IMHO. Who knows, maybe I'll win a Nobel prize for this hypothesis (ha ha).