Hydrogen has a oxidation number of 1, just as do the alkali metals, and so it is placed there. Hydrogen can also have an oxidation number of -1, as do the halogens, and so it is sometimes placed above F and right before He. The periodic table on my wall (in my classroom) is from Fisher Scientific and has hydrogen in both places.
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The position of hydrogen in the traditional form of the periodic table is at the head of Group 1 (the alkali metals) based on the similarity of the valence shells of this family: each of the elements possesses a half-filled s-orbital, namely, H 1s1, Li 2s1, Na 3s1, etc. However, the properties of hydrogen differ significantly from those of the other elements in Group 1. Hydrogen is a gas, not a reactive metal. The hydrogen ion, H+, plays an extraordinary and characteristic role in acid-base chemistry by virtue of its size and mass. Non-metals with electronegativity comparable to that of hydrogen form covalent bonds with that element resulting in volatile molecular substances. In contrast, compounds of the alkali metals and the non-metallic elements are ionic. Furthermore, hydrogen will accept electrons from the electropositive elements of Groups 1 and 2 to form salt-like hydrides comparable to the salts formed by the reaction of the halogens with these electropositive elements. Thus, some authors place the symbol for hydrogen at the head of Group 1 and also at the head of Group 17.
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Says who? There's nothing wrong with Hydrogen's position in the table.