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Name: Linda K. griffin's sixth grade science class
Status: N/A
Age: N/A
Location: N/A
Country: N/A
Date: 1999 


Question:
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?



Replies:
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 electron shell.

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.

-dr topper



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