Electron affinity is the change in energy that occurs when an electron is added to a neutral atom in the gaseous state to form a negative ion.

Factors affecting electron affinity:

* Atomic size: As atomic size increases, the electron affinity generally decreases. This is because the outermost electron is farther from the nucleus and experiences weaker attraction.

* Nuclear charge: As nuclear charge increases, the electron affinity generally increases. This is because the nucleus exerts a stronger attraction on the incoming electron.

* Shielding effect: Electrons in inner shells shield the outer electrons from the nucleus, reducing the attraction.

In the case of iodine and bromine:

* Iodine is larger than bromine.

* Both iodine and bromine are in the same group (halogens) and have similar nuclear charges.

Due to its larger size, the outermost electron in iodine is farther from the nucleus and experiences weaker attraction compared to bromine. This results in a lower electron affinity for iodine compared to bromine.

Therefore, iodine has a higher electron affinity than bromine.