The document outlines the order of overlap of atomic orbitals, ranking them as I2 > IBr > ICl > IF based on their extent of overlap. I2, as a homonuclear diatomic molecule, has the best overlap due to the similar atomic sizes of the iodine atoms, while IBr has good overlap between iodine and bromine despite being from different periods. ICl exhibits moderate overlap, and IF has the least overlap due to significant size differences between iodine and fluorine.