Draw the best Lewis structure for ICl5.
The Correct Answer and Explanation is :
The Lewis structure for iodine pentachloride (ICl₅) can be drawn by following these steps:
- Count Valence Electrons: Iodine (I) has 7 valence electrons, and each chlorine (Cl) has 7 valence electrons. For ICl₅, the total number of valence electrons is:
[
7 \, (\text{from I}) + 5 \times 7 \, (\text{from Cl}) = 7 + 35 = 42 \text{ valence electrons}
] - Determine the Central Atom: Iodine is less electronegative than chlorine and will be the central atom.
- Connect Atoms: Place iodine in the center and draw single bonds to each of the five chlorine atoms. This uses 10 of the 42 valence electrons (2 electrons per bond), leaving 32 electrons remaining.
- Distribute Remaining Electrons: Each chlorine atom requires 6 more electrons to complete its octet (3 lone pairs), using 30 electrons. After placing these lone pairs, there will be 2 electrons left.
- Place Remaining Electrons: The last two electrons are placed as a lone pair on the iodine atom. Thus, the final structure has iodine surrounded by five chlorine atoms and one lone pair.
- Verify Octets: Each chlorine has a complete octet (8 electrons), and iodine has 12 electrons (10 from bonding and 2 as a lone pair), which is acceptable since iodine is in the third period and can expand its octet.
Summary of the Structure:
- Shape: The structure is a square pyramidal geometry due to the presence of a lone pair on iodine and five bonding pairs to chlorine.
- Bond Angles: The bond angles between the chlorines are 90 degrees, and the axial chlorine is above and below the plane formed by the four equatorial chlorines.
This Lewis structure illustrates that ICl₅ can accommodate more than 8 electrons around the central atom (iodine), demonstrating its ability to expand its valence shell, which is a common characteristic of elements in the third period and beyond.