Hydrogen and the Alkali Metals Um...hydrogen isn't a metal, is it? No, it isn't; hydrogen itself is not considered to be one of the alkali metals. Its place in the table does make sense, though; hydrogen tends to behave like the other members of its column in chemical reactions. For example, all these elements combine with oxygen to form compounds with the formula X2O. I'm not quite sure what you mean by X2O. X is a stand-in for the chemical symbol of any of the elements in this column. In the case of hydrogen, the formula becomes H2O, which of course is just water. Later on, you'll see exactly why hydrogen belongs in this particular place in the periodic table.

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