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

Homework Help: Largest lattice energy

  1. Nov 15, 2007 #1
    1. The problem statement, all variables and given/known data

    Which one of the following ionic compounds has the largest lattice energy?


    2. Relevant equations
    Ionic/Atomic size
    The smaller the ionic size, the larger the lattice energy.
    Size increases from right to left, increases top to bottom of periodic table

    3. The attempt at a solution
    I've tried to compare the like ionic compounds, such as NaCl with CaCl2 but I can't seem to figure out which is bigger--Na+ or Ca2+

    Am I approaching this incorrectly?
  2. jcsd
  3. Nov 15, 2007 #2
    Well if your losing electrons then the atomic size would what?
  4. Nov 15, 2007 #3
    Loss of electrons means smaller atomic radius. But Na and Ca don't have the same number of protons so isn't there another way to have to look at it?
  5. Nov 16, 2007 #4
    Well the loss of electrons makes the radius smaller. You know Na is one of the bigger elements size wise right? And the size decreases as you go across the periodic table. The protons don't attract the valence electrons as much as the core electrons b/c of shielding. Do you get it now?
  6. Nov 17, 2007 #5
    are you considering charges?

    L.E. is directly proportional to product of charges on ions but inversely proportional to sum of ionic radii.

    hope it helps
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook