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

Solids are solids

  1. Feb 24, 2005 #1
    Rutherford's idea that atoms are mostly empty space is retained in all subsequent atomic theories. So, how can solids be solids? How can a chair support you, why don't you fall through.

    Is it because the atoms are so close together??
  2. jcsd
  3. Feb 24, 2005 #2


    User Avatar
    Science Advisor
    Homework Helper

    Relative distance between atoms/molecules wrt atomic/molecular sizes and intermolecular bonds are decisive.

    From this perspective,e.g. the solide state is fundamentally different from the gaseous one.

  4. Feb 24, 2005 #3


    User Avatar

    Staff: Mentor

    While there is a lot of space between atoms, they are built out of the charged particles; Coulomb forces don't allow them to get to close one to each other. In general it is similar effect to that of two strong magnets - if taken S to S or N to N they are difficult to press together, even if there is nothing between them.

    Chemical calculators for labs and education
    BATE - pH calculations, titration curves, hydrolisis
  5. Feb 24, 2005 #4
    I dont get it :(
  6. Feb 26, 2005 #5


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    All forces that are classified as "contact" forces, i.e. forces that involve interaction between matter (such as your butt and the surface of the chair), forces like friction, the "normal" force that keeps you from falling through the floor, the chemical forces that bind molecules together, the force of impact between two colliding billiard balls et cetera...all of these forces are electromagnetic in nature. They are due to electromagnetic interactions between the particles that make up the matter in question. You can't pass your hand straight through a wall, because then atoms in your hand would be trying to occupy the same space as atoms in the wall, and so one or the other would have to move...instead the atoms mutually repel each other. With fluids, the atoms are not tightly held in some sort of rigid structure (as in solids) that requires a huge force to break. Instead, they can move, and are easily displaced as your hand passes through the substance.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook