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Actually there are three types of hydrogen atoms. The most common type is "normal" hydrogen and only has 1 proton and 1 electron. A less abundant type, called deuterium contains 1 proton, 1 electron, and 1 neutron. A deuterium atom weighs twice as much as a "normal " hydrogen atom. There is also an even less abundant type of hydrogen atom, called tritium which contains 1 proton, 1 electron, and 2 neutrons. Tritium weighs three times as much as a "normal" hydrogen atom. For most purposes, all three of these types of atoms behave identically from a chemical perspective. However, from a nuclear perspective, they behave differently since they have different numbers of neutrons. Hydrogen is not in the noble gas family because its s orbital in its outermost shell (The first shell) is not filled. Members of the noble gas family have filled s and p orbitals in their outermost electron shell.>>>>http://www.newton.dep.anl.gov/askasci/chem99/chem99057.htm