Triiodide ion (I3-) - Lewis Structure
In the lewis structure of triiodide ion (I3-), there are two I-I bonds. and one iodine atom is located as the center atom. Each iodine atom has 3 lone pairs and center iodine atom have -1 charge. We will learn how to draw the lewis structure of I3- step by step in this tutorial.
I3- lewis structure
Lewis structure of I3- is given above and you can see how atoms are joint with each other. One iodine atom has located as the center and other two iodine atoms are located around it.
Steps of drawing lewis structure of I3-
There are several steps to draw the lewis structure of the I3- ion. Each step is explained in detail in the remaining part of this tutorial.
- Find total number of electrons of the valance shells of Iodine atoms
- Determine total electrons pairs as lone pairs and bonds
- Find center atom and basic sketch
- Mark lone pairs on atoms
- Mark charges on atoms if there are charges.
- Check the stability and minimize charges on atoms by converting lone pairs to bonds to obtain best lewis structure.
Total number of electrons of the valance shells of I3-
There are only one element in I3- ion; Iodine. Iodine is a group VIIA element and has seven electrons in its valence shell.
- valence electrons given by Iodine atoms = 7 * 3 = 21
- Due to overall charge of -1, one more electron should be added to total number of valence electrons.
- Total valence electrons = 21 + 1 = 22
Total valence electrons pairs of I3-
Total valance electrons pairs = σ bonds + π bonds + lone pairs at valence shells
Total electron pairs are determined by dividing the number total valence electrons by two. For, I3- ion<, total pairs of electrons are eleven (22/2) in their valence shells.
Selection of center atom and skeletal of I3-
To be the center atom, ability of having greater valance and being most electropositive element in the molecule are important facts. These are not essential. But those two facts play a major role in selecting center atom of a molecule or ion in a covalent compound.
However, I3- only contain Iodine atoms, there is no issue in selection of center atom.
Determine lone pairs on atoms
After deciding the center atom and skeletal of skeletal of I3- ion ion, we should mark lone pairs on atoms. Remember that, there are total of eleven electron pairs to mark on atoms as bonds and lone pairs.
- There are already two bonds in the above drawn skeletal. Now only nine (11-2) electron pairs are remaining to mark on atoms.
- Usually, those remaining electron pairs should be started to mark on outside atoms. Therefore, mark electrons pairs on outside iodine atoms; Each iodine atom will take three lone pairs. Now, six electron pairs are marked on outside two iodine atoms.
- Now, there are three remaining lone pairs and they should be marked on center iodine atom.
Mark charges on atoms and check the stability and minimize charges on atoms by converting lone pairs to bonds
There is a -1 charge on center Iodine atom and this structure can consider as the most stable structure we can draw for I3- ion. Therefore, we do not need to convert lone pairs to reduce charges.
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