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Homework Help: Why are noble gases, gases?

  1. Apr 24, 2008 #1
    [SOLVED] why are noble gases, gases?

    1. The problem statement, all variables and given/known data
    this has bothered me for some time,
    what determines the density of an element at normal atmoshpheric conditions?
    and more importantly what determines if a substance at s.t.p is a gas solid or liquid

    2. Relevant equations

    gas laws, maybe?

    3. The attempt at a solution

    i was thinking there might be some repulsion and atractions between atoms, like with Ar it contains a full outer shell which means to gain more electrons it would require a new level which would take alot of energy, compared to Sulfur which is trying to complete a full outer shell, which reqiures less energy. so there is more atractration between atoms.
    this only can aply for some atoms, help?
  2. jcsd
  3. Apr 24, 2008 #2
    have you done anything on the different types of intermolecular force yet? If so, you will easily realise partly why the noble gases are, in fact, gases. The "density" of an element is a bit of a funny thing to be talking about, because in gas terms we generally don't talk about density in the same way (we don't say there is so many kg/m^3 of argon, we say there are so many ppm or ppb.
    Looking at your posts so far it seems you have phrased everything only in terms of electron shells. Admittedly I find that just about all chemistry (apart from physical chemistry) can be explained by electron shells (hence why I'm more of a physicist), but maybe you should wait a little while and things will become clearer to you.

    In argon, and indeed any element you have only weak van der waals forces between particles, so that's why most of the non-metals are in fact gases, until you get up to really heavy stuff.

    Attraction and repulsion between atoms has absolutely nothing to do with how hard they are "trying to complete a shell". If you want to understand more, look up intermolecular forces and how they work. It should be very soon part of your chemistry course.

    And finally, re your other post, this should definitely be in the chemistry subforum.
  4. Apr 24, 2008 #3
    ok, thanks for your time.
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