- #1
kel
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Homework Statement
The ionisation energy of Li is 5.39eV and the electron affinity of F is 3.40eV. Give a lower bound for the modulus of the crystallisation energy of Li+F-
Homework Equations
Not entirely sure of the equation to use, but have this one in my notes:
U = - (q1q2/r(1,2)) . alpha . (1 / 4Pi E)
where E is the permeability of free space (I believe)
The Attempt at a Solution
I haven't really attempted this to any meaningful degree, the problem is that I don't know how I can work this out when I'm not given a value for r (presumably the radius between atoms or ions??) nor am I sure what values I'm supposed to use for the charges q1 and q2.
I don't expect anyone to solve this for me, but if you could clarify what you think I need to do to work this out I'd be greatful. My lecturer is great on giving derivations and formulas, but never seems to explain things very well.
Cheers
Kel