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A fourth question

  1. Mar 2, 2005 #1
    What is the molecular spacing of common items such as water, wood, copper, hydrogen, helium, glass (silicon), oxygen and iron in femtometers?
  2. jcsd
  3. Mar 2, 2005 #2


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    Copper and iron do not have molecules. But their lattice parameters are about 3 to 4A.
    Glass is mostly silicon dioxide (not silicon), which is amorphous and hence doesn't have lattice parameters. Typical atomic spacings will be from 3 to 15A, and again, you do not have well-defined molecules.

    Water is a liquid with reasonably strong hydrogen bonding. An estimate from the density of water ar room temperature gives me about 3.2A as the distance between molecular centers. But since the interatomic spacing in the molecule itself is of order 1A, there really is very much more space "between" molecules as there is between atoms in a molecule.

    Hydrogen and helium and gases, and their intermolecular spacing is a strong function of temperature and pressure. At NTP it is about 34A.

    In wood, nearest neighbor distances can be anywhere from 3 to 30A.
  4. Mar 6, 2005 #3
    Thank you very much. Do you know the spacing of the protons and electrons in hydrogen, and the spacing of protons, neutrons and electrons in helium?
  5. Apr 3, 2005 #4
    Last part of question

    The third and obvious part of this fourth question would be the spacing between the various quantum levels of the various elements. Probably easy for hydrogen and helium, more difficult as we go 'up the scale'. I have a theory about it but I'll wait for others to respond before I lay my ignorance on the table for others to see. I do hope to get some response from this. I'm willing to look foolish to gain more knowledge. I hope others are willing to abase themselves a little in order to expand their understanding. There is really no reason not to. If someone patronizes you or tries to denigrade you on a public forum, then just ascribe it to their arrogance and recognise that they are people of low self esteem and character. The knowledge and understanding is more important than anybody's ego. If there are people who have the answers to this question, but are bound by a secrets act, then please try not to engage in a misinformation effort. Just do us all a favor and remain silent. Hope for some response.

    The reason for asking for these distances in femtometers instead of angstroms was because I thought that by the time we got to quantum levels it would easier to express these distances in whole numbers rather than decimals. It provides a common thread of measurement for all of the distances that also provides a better visual picture of these distances.

    One last note for the site managers... All science has political, military and spiritual implications and ramifications. Otherwise, you would not be trying to protect secrets. Maybe you could open up a little for the benefit of everyone. Do you have a section in this forum that allows for these types of discussions? I haven't perused it in awhile so maybe I missed it.

    Douglas Lockwood
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    Last edited: Apr 3, 2005
  6. Apr 4, 2005 #5


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    This may be obvious to someone who knows you, but to the rest of us, it is neither obvious nor sensible in any way.

    "Quantum levels" are separated in energy, not in space (at least, that is the what one usually means by a "spacing between the levels"). So, if you are using standard terminology in a non-standard manner, please provide definitions of "your terminology".
  7. Apr 5, 2005 #6


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    This may help -

    Atomic radii - http://www.webelements.com/webelements/elements/text/H/radii.html
    One will find atomic radii for all element. For H and He, 53 pm and 31 pm ( 1 pm = 1 picometer = 1000 femtometers), respectively. These are the effective distance between electrons and nucleus.

    or alternatively - some fundamental nuclear and atomic constants


    Paper on the proton 'radius' - http://arxiv.org/PS_cache/hep-ph/pdf/9712/9712347.pdf [Broken] - about 0.890(14) fm, from Garching, 1997, using hydrogen Lamb shift measurements.

    As the paper indicates, this is really a charge radius determined by the charge distribution inside the proton.

    Pion range of strong force = 0.73 x 10 fm = 0.61 x classical proton radius.

    Survey of scattering inside nuclei - some idea of subatomic distances - http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/scatsurv.html#c1
    Last edited by a moderator: May 2, 2017
  8. Apr 7, 2005 #7


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    As Gokul said, it's better to characterize electrons as having energies rather than distances from the nucleus. However, one can give a rough size for the atom, that being the Bohr radius, which is about 0.5 A. The components of nuclei (protons and neutrons) are also better expressed by quantum mechanical energy states, but the rough size is about one hundred thousandth of the Bohr radius.
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