The lack of a neutron in hydrogen
Name: Linda K. griffin's sixth grade science class
We would like to know why hydrogen has only a proton
and no neutrons. Does the lack of a neutron influence
hydrogen's volatile properties? Also, is the lack of a
neutron the reason that hydrogen is not grouped with
the noble gases?
Excellent question... 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
Hope this helps!
Dr. Brown from Tallahassee...
Well, helium has only filled s orbitals but it's usually
the first two is said to have a "restricted valence;" only
the s orbitals are considered to be part of the valence shell.
Thus the hydrogen atom has it s valence half-filled and
He has its valence completely filled, which is characteristic
of rare-gas elements; low electron affinity, high ionization energy.
In the second row, s and p orbitals are close enough in energy
so that they now constitute the valence shell; thus when
beryllium's 2s orbital is filled it still hasn't completed it's
valence shell (although the filled 2s orbital is pretty stable and
is sort of a pseudo-rare gas configuration....
Just putting in my 2 cents' worth.
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Update: June 2012