Describe the molecular shape ofi03
? trigonal planar ? trigonal pyramidal ? tetrahedral ? bent
The Correct Answer and Ex1planation is:
The molecular shape of IO3⁻ (iodate ion) is trigonal planar.
To understand this, we need to analyze the electron and molecular geometries of the iodate ion. The iodate ion consists of an iodine atom (I) bonded to three oxygen atoms (O) with one negative charge, making it an ion (IO3⁻). Here’s how we can determine the geometry:
- Electron Geometry:
The iodine atom in IO3⁻ has three bonding pairs (each from the three oxygen atoms) and one lone pair of electrons. The presence of three bonding pairs and one lone pair of electrons around the iodine atom suggests a total of four electron pairs around iodine. - Molecular Geometry:
When we consider the positions of the atoms (ignoring the lone pair), the iodine atom forms three bonds with oxygen atoms. The ideal geometry for four electron pairs is tetrahedral. However, since we only care about the positions of the atoms and not the lone pair of electrons, the geometry becomes trigonal planar, as the three bonds are spread as far apart as possible in a 120° angle in the plane. - Formal Charge Considerations:
Each oxygen atom typically follows the octet rule, while iodine, being a larger atom, can hold more than eight electrons. In IO3⁻, iodine has an expanded octet, and the negative charge is delocalized over the oxygen atoms, helping to stabilize the trigonal planar geometry.
Thus, the molecular shape is trigonal planar because the three oxygen atoms are arranged symmetrically around the central iodine atom in a flat, triangular configuration. This is the most stable geometry based on the distribution of electrons and the bonding patterns in the iodate ion.
