Answer:
Triiodide molecule (I₃⁻) has sp³d hybridization
The number of sigma (σ) bonds = 2
and the number of Pi (π) bonds = 0
Explanation:
In a Triiodide molecule (I₃⁻), three iodine atoms combine to form a linear and symmetrical polyhalogen ion. The triiodide ion (I₃⁻) is formed by the chemical reaction of diatomic iodine (I₂) with iodide ion (I⁻).
The involved chemical reaction: I₂ + I⁻ ⇌ I₃⁻
<u>The structure of the triiodide ion:</u> [ I − I − I ]⁻
As we know, that an iodine atom has 7 valence electrons.
To complete its octet, if the central iodine atom accepts an electron to form an iodide ion, thus having 8 valence electrons.
Then this central iodide bonds with two terminal iodine atoms by sigma (σ) bonds. So, the number of non-bonding electrons on the central iodide ion is 6.
<em>Thus, the number of lone pairs on the central iodide atom = 3</em>
<em>Also, the number of sigma (σ) bonds = 2</em>
<em>and the number of Pi (π) bonds = 0</em>
<u>Now, the hybridization of this molecule can be determined by the steric number.</u>
Steric number = number of σ bonds + number of lone pairs = 2 +3 = 5 ⇒ sp³d hybridization
<u>Therefore, the Triiodide molecule (I₃⁻) has sp³d hybridization.</u>
