Answer to Question #119080 in Chemistry for ThTo

Question

Iodine dissolves in an aqueous solution of iodine ion's to form triiodide .this ion's consist of one one iodine atom bonded to two others. Describe the bonding of triiodide in terms of valance bond theory ?

Answer 1

The element iodine has 7 electrons in its valence shell: 5s²5p⁵. Therefore, it needs one more electron to follow the octet rule. There are three iodine atoms in triiodide ion, and the central atom has one extra electron: its charge is -1. Therefore, the central atom has 8 electrons in its valence shell. In sum, these three atoms have 7+7+8=22 electrons in their valence shells. The electron dot formula of I₃^- is:

The central atom has 5 pairs of electrons in its valence shell. Therefore, its hybridization is sp³d. Each I-I bond is formed by the overlap of an orbital sp³d of the central iodine with singly occupied p-orbitals of the lateral iodines. This can be summarized as follows:

where the red arrows represent the electrons of the lateral iodine atoms.