Lewis Structure of N2O4 (Dinitrogen tetroxide) - Drawing Steps
Dinitrogen tetroxide is a one of the oxide of nitrogen and are two nitrogen atoms are located at center of the molecule. In Lewis Structure of N2O4, two oxygen atoms have connected to one nitrogen atom. There are charges on atoms in Lewis Structure of N2O4.
Now, we are going to learn, how to draw this lewis structure step by step. You need to follow several guidelines to obtain best lewis structure.
Steps of drawing N2O4 lewis structure
Lewis Structure of N2O3 is different from simple molecules because there is a problem of thinking what is the sketch of N2O3 molecule. This means, how atoms are located in the molecule.
Following steps should be followed to draw N2O3 lewis structure and they are explained in detail in this tutorial.
- Find total number of electrons of the valance shells of nitrogen atoms and oxygen atoms
- Determine total electrons pairs
- Center atom selection from nitrogen and oxygen atoms
- Put lone pairs on atoms after sketching the molecule structure
- Stability of lewis structure - Check the stability and minimize charges on atoms by converting lone pairs to bonds to obtain the best lewis structure.
Drawing correct lewis structure is important to draw resonance structures. Otherwise, you will be in trouble to draw stable resonance structures and resonance hybrid.
Total number of electrons of the valance shells of nitrogen and oxygen atoms and charge of the anion
There are two nitrogen atoms and three oxygen atoms in the dinitrogen tetroxide molecule. There is no overall charge in the molecule.
Nitrogen and oxygen are located at VA and VIA groups respectively in the periodic table. So nitrogen has five electrons in its valence shell. In oxygen atoms, they have six electrons in their valence shells.
- Total valence electrons given by two nitrogen atoms = 5 * 2 = 10
There are three oxygen atoms, Therefore
- Total valence electrons given by four oxygen atoms = 6 *4 = 24
- Total valence electrons = 10 + 24 = 34
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, N2O3, there are 34 valence electrons, so total pairs of electrons are 17.
Center atom of N2O3
To be the center atom, ability of having greater valance is important. Therefore nitrogen atoms have more chances to be the center atom (See the figure). But, there is two nitrogen atoms in this case. So, now we can build a sketch of N2O4 molecule.
Mark lone pairs on atoms
There are already four N-O bonds and one N-N bond in the above sketch. So, five (4+1) electron pairs are used in the sketch. Therefore only twelve (17-5) valence electrons pairs are remaining to draw the rest of molecule.
Start to mark twelve ten valence electrons pairs on outside atoms (oxygen atoms) as lone pairs. One oxygen atom will take three lone pairs following the octal rule (oxygen and nitrogen atoms cannot keep more than eight electrons in their valence shells).
Four oxygen atoms will take twelve valence electrons pairs. Now all lone pairs are finished and no lone pair or pairs to mark one nitrogen atoms.
Mark charges of atoms
Now you should mark charges on atoms. However summation of charges of every atoms should be zero because this molecule does not have an overall charge like an ion.
Check the stability of drawn N2O4 structure and reduce charges on atoms by converting lone pairs to bonds
The drawn structure for N2O4 is not a stable one because all oxygen atoms and nitrogen atoms have charges. To be the best lewis structure, charges of atoms should be minimized.
Now, we should try to minimize charges by converting lone pair(s) which exist on oxygen atoms to bonds. So we convert one lone pair of one oxygen atom as a N-O bond (see the figure).
Now there is a double bond between one nitrogen and one oxygen atom. Still other bonds are single bonds.
In new structure, charges of atoms reduced. Now there is no any charge on one oxygen atom. Also, charge of one nitrogen atom is reduced from +2 to +1.
But, still there are charges on atoms. If you can, you should try to convert one more lone pair on another oxygen atom to a bond. Yes. We can do that like following figure.
Charges of atoms are reduced furthermore and we got a stable structure. Therefore, we can consider, this is the best structure for Lewis structure of N2O4.
Best lewis structure of N2O3
