Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Can atom sizes be altered?

  1. Sep 17, 2015 #1
    Hello all, this is the first forum i have ever been on so please bare with me, i have so many questions to ask but i would like to start with the size of atoms, can there size be altered? are they all the same size?
     
  2. jcsd
  3. Sep 17, 2015 #2

    blue_leaf77

    User Avatar
    Science Advisor
    Homework Helper

    First of all, atoms should not be viewed as being a bulky ball or other bulk shaped object. Quantum mechanics does not allow such picture. However in practical sense, people do often talk the size of the atom, usually this is referred to the radius with the highest chance to find the valence electron.
    Rather than size, it is more appropriate to say electron distribution instead. By applying external fields, e.g. electric or magnetic field, The shape of the electron distribution around the nucleus will be altered.
    Different atoms have different number of electrons, so their "size" cannot be the same.
     
  4. Sep 17, 2015 #3
    I actually did think of them as little balls, lol, but can there can be a single atom on its own?
     
  5. Sep 17, 2015 #4

    blue_leaf77

    User Avatar
    Science Advisor
    Homework Helper

    Then you should start to change the way you imagine it.
    What do you mean by single atom on its own?
     
  6. Sep 17, 2015 #5
    please bare with me if im sounding uneducated i haven't read much on this subject, if some thing is made up of atoms then this would suggest to me that there are many of these things that make up some thing larger, am i understanding this all wrong?
     
  7. Sep 17, 2015 #6

    blue_leaf77

    User Avatar
    Science Advisor
    Homework Helper

    Don't worry, the starting point of learning things is always not knowing things.
    It's just because our eyes do not have the ability to resolve the nanoworld of atoms and molecules that makes bulk matter look static and perfect solid. In fact, various dynamics is taking place down there with the time scale ranging from several hundred of femtoseconds down to attoseconds.
     
  8. Sep 17, 2015 #7
    the reason i was asking about one on its own is i was wondering why they are the size that they are but i have just watched a video that says that the electrons orbiting the nucleus could be any where but they stay mainly close to the nucleus is this correct?
     
  9. Sep 17, 2015 #8

    blue_leaf77

    User Avatar
    Science Advisor
    Homework Helper

    That's another way of saying that electrons in an atom does not have a strict shell containing them such that they cannot escape out of it. The electrons can be found anywhere around the nucleus and our current theory states that you have nonzero probability to find them far far away from the nucleus only that it's much smaller than finding it closer to the nucleus thanks to the binding potential.
     
  10. Sep 17, 2015 #9
    so if we had a marble, the marble is made of a silly amount of atoms but am i right in saying that the electrons can exist outside of the marble then?
     
  11. Sep 17, 2015 #10

    blue_leaf77

    User Avatar
    Science Advisor
    Homework Helper

    Strictly speaking yes. Practically, no. Typical probability density to find electrons around the nucleus already fall off considerably within a fraction nanometers.
     
  12. Sep 17, 2015 #11
    when i was asking about the atoms size it was because i had a random thought that if we could could control the size of an atom we could control the size of an object, i feel like ive been reading too much sc fi now
     
  13. Sep 17, 2015 #12

    blue_leaf77

    User Avatar
    Science Advisor
    Homework Helper

    Increasing the distance of a valence electron from the nucleus is possible through electronic excitation, but it won't last long, it will quickly go back to its stable state.
     
  14. Sep 17, 2015 #13
    There are some atoms which have no valence electrons.
    The electrons they have are exactly the right number to fill one or more orbital shells.
    Atoms of the element Helium having just two electrons in one shell is the simplest example.
    Atoms of these elements are very disinclined to associate with any other atoms and happily exist just as they are.
    They don't usually react chemically with any other atoms, not even atoms of their own type.
     
    Last edited: Sep 17, 2015
  15. Sep 20, 2015 #14

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    You can apply a high pressure. This compresses the material, it also compresses the atoms (for every reasonable definition of a size of an atom in this material). There is no magical switch which would change the size of atoms, however.
     
  16. Sep 21, 2015 #15
    An atom can never exist in single way on its own. We say it an atom only because it consists of nucleons and other sub - atomic particles. If there were no sub - atomic particles, there would be no atoms. Got it? :)
     
  17. Sep 21, 2015 #16
    Actually electrons can not be found outside of marble. But only when we apply high energy on an atom, it's electrons starts jumping to high level orbits and when electrons are at highest level, they either go back to lower levels giving out radiations or they jump out from an atom.
     
  18. Sep 21, 2015 #17

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    I think he was asking about isolated atoms with nothing else around. Those exist, of course. Helium gas is a collection of many single atoms, for example.
    They can, as the wave function doesn't have a fixed boundary.
     
  19. Sep 22, 2015 #18
    Curiosity: does it have any asymptote at all? Is the possibility that it could end up a light year away but still bound to the atom in a quantum way greater than zero?
     
  20. Sep 22, 2015 #19

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    In an ideal world where nothing apart from the marble exists and the marble exists forever, the amplitude is non-zero even 1 light year away. Its value is completely negligible, of course.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Can atom sizes be altered?
  1. Atom size (Replies: 3)

Loading...