Question

iodide ion is a good nucleophile as well as good leaving group? explain or give reason?
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Answer 1

Answer:

Iodine is a better leaving group than other halogen atoms due to its larger size. Due to larger size, charge density decreases and it becomes stable. So, its a better leaving group.

Hope it helps you

Answer 2

The iodide ion is a good nucleophile because it has a large atomic radius. As you go down the halogen group, the proton number increases and there is more shielding of the outer electron from the nucleus from more full inner electron shells. The increase in shielding is more significant than the increase in proton number, thus the outermost electron is further away from the nucleus at a higher energy level (it has a higher intrinsic energy) and the size of the electron cloud is bigger. This means that halogens further down the group are more polarisable, as the electrons of the anion (the electron cloud) are more easily distorted and drawn away from the anion, as they are further away from the positive nucleus so there is a lower electrostatic force of attraction between the outer free out electrons and the nucleus. Therefore, I- is a good nucleophile and a better nucleophile than F-, Cl-, and Br- as it is more able to donate a pair of its outer electrons to an electrophile, forming a dative covalent bond.