From Wikipedia,
the free encyclopedia
The Madelung constant is
used in determining the
energy of a single
ion in a
crystal. It is named after
Erwin Madelung, a German
physicist.
An ionic solid has a certain
amount of energy that is
associated with it, because the
ions don't want to be separated.
It will take a positive energy to
break apart the ionic solid. This
value is known as
lattice energy which is the
exact negative of the energy of
crystallization.
The lattice energy describes
the amount of energy for a whole
crystal but it doesn't describe
the energy contribution of a
single ion in the crystal. The
energy of a specific ion would
depend on how close it was to
other ions, how many had the same
charge, and how many had the
opposite charge.
Since charges in ions are based
on the electric energy of an
electron, we can use the
energy of the electron and then
modify it to see how close the
other electrons are.
- z = charge of ions
- e = 1.6022×10−19
C
- 4πEo = 1.112×10−10
C²/(J m)
- M = Madelung's constant,
which is a relationship of the
distance of the ions from one
another due to a specific type
of crystal.
