Hydrogen is a very special element of the periodic table and doesn't belong to any family. While hydrogen sits in Group I, it is NOT an alkali metal.
Hydrogen is the lightest element. It is by far the most abundant element in the universe and makes up about about 90% of the universe by weight. It is also the most abundant element in the earth's sun. Hydrogen as water (H2O) is absolutely essential to life and it is present in all organic compounds. Hydrogen is the lightest gas
Hydrogen, though listed in Group 1 due to its electronic configuration, is not included in the alkali metals since it rarely exhibits similar behavior. Hydrogen is a special case, because even though it does have the defining characteristic of all group 1 elements, which is that it has one valence electron, it is physically very different from all the other group 1 elements. As you move down from Hydrogen to the Alkali metals the atomic radius increases, because each successive Period (row) has an additional energy level. You can think of it this way: each time you drop down a row, you add a "ring." Hydrogen (at normal temperatures and pressures) is a gas, and all the other group 1 elements are solid metals. As a result, most forms of the periodic table show hydrogen above the rest of the table, in its own special place.