MnO4- (Permanganate) Ion Lewis Structure | Steps of Drawing
Permanganate ion (MnO4-) is an oxyanion of manganese and have a -1 charge.
lewis structure contains three Mn=O bonds and one Mn-O bond. Three are three oxygen atoms which made double bonds with manganese atom. Each of those oxygen atom has two lone pairs. Other oxygen atom has three lone pairs with a -1 charge. Manganese atom is the center atom in MnO4- ion. Steps of drawing the lewis structure of MnO4-are explained in detail in this tutorial.
Lewis structure of MnO4- ion
You can see there is only -1 charge in one oxygen atom. All other oxygen atoms have made double bonds with center manganese atom.
Steps of drawing the lewis structure of MnO4- ion
There are several steps to draw a lewis structure of a molecule or ion. Because MnO4- ion is a bit complex ion, most of those basic steps are used. So, you can learn good basic things of drawing lewis structures from this example.
- Find total number of electrons of the valance shells of manganese and oxygen atoms
- Total electrons pairs as lone pairs and bonds
- Center atom selection
- Mark lone pairs on atoms
- Mark charges on atoms if there are charges on atoms.
- 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 N3- ion
Manganese has seven valence electrons while oxygen has only two.
To find out total valence electrons given by a particular element, you should multiply number of electrons of the valance shell by the number of atoms of that element in respective molecule.
- valence electrons given by manganese atom = 7*1 = 7
- valence electrons given by oxygen atoms = 6*4 = 24
Because there is a -1 charge in MnO4- ion, an extra electron is received to total valence electrons.
- electrons received due to -1 charge = 1
- Total valence electrons = 7 + 24 + 1 = 32
Total valence electrons pairs
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, MnO4- ion, total pairs of electrons are 16.
Determine center atom and basic sketch of MnO4- ion
To be the center atom, ability of having higher 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 an ion.
We know manganese should be the center atom because manganese has the highest valence from manganese and oxygen. Also, manganese is more electropositive than oxygen.
mark lone pairs on atoms
Now, we know the center atom and basic sketch of MnO4- ion. As the next step, we mark lone pairs on atoms. Remember that, there are total of 16 electron pairs as bonds and lone pairs in MnO4- ion.
- There are already 4 Mn-O bonds in the above drawn sketch. Now only 12 (16-4) electron pairs are remaining to mark on atoms.
- Usually, those remaining electron pairs should be started to mark on outside atoms (in this case, on oxygen atoms). Each outside oxygen atom will take 3 lone pairs and total of 12 electron pairs can be marked on all outside four oxygen atoms.
- Now, all remaining lone pairs are marked and there are no lone pairs to mark on center manganese atom (that is not a problem).
Mark charges on atoms and check the stability and minimize charges on atoms by converting lone pairs to bonds
After marking lone pairs on atoms, there are charges on every oxygen atoms and manganese atom and it's shown below.
Having such charges on atoms is not good for stability of a molecule or ion. Therefore, we should try to reduce charges on atoms by converting lone pairs to bonds in possible occasions. For MnO4-, we are doing it like following.
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