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Homework Help: Finding attractive force between two ions, using Coulombs equation

  1. Jan 21, 2013 #1
    1. The problem statement, all variables and given/known data

    "Calculate the force of attraction between a K +
    and an O 2- ion whose centers are separated
    by a distance of 1.5 nm."

    2. Relevant equations

    F = [ k (Z1)(Z2) ] / r^2

    3. The attempt at a solution

    Both valences are filled when K is a + charge and O is a 2- charge. My main problem is I don't know what to use for "Z". I would just use 1 and -2, but the shells are filled and maybe there isn't much attraction at all?

    Any help is greatly appreciated, thanks!
  2. jcsd
  3. Jan 21, 2013 #2


    User Avatar

    Staff: Mentor

    You have two IONS - one has charge +1, the other -2. Valences, shells don't matter.
  4. Jan 21, 2013 #3
    You have the charges, you have the distances, and that's what the formula asks for. Just because these are atomic-level particles doesn't mean squat - they are charged particles. Use the formula.
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