I am trying to calculate the lattice energy of $\ce{CaBr2}$, I am uncertain of how to incorporate the electron affinity value provided for $\ce{Br2}$ into my calculation.
Since electron affinity is the negative of the energy change that occurs when an electron is accepted by an atom in a gaseous state in the form of an ion, will I have to take the negative value of electron affinity and double it?
At this point in the Born-Haber Cycle $\ce{Br2}$ is already dissociated, and since calcium looses two electrons while forming $\ce{CaBr2}$, would it be logical for the total energy change to be a (negative) double of the electron affinity of bromine ?
