How many electrons will be shared?

Suppose we are to make a bond drawing of a covalent bond between two nitrogen atoms. How would we know how many electrons are shared in each (3)? Do we just logically look at it and see how many electrons are in each and figure out what we need to do to make it stable? I have two Lewis dots of each … But now what? How do I know which ones are shared?




By looking at the periodic table, you can see that Nitrogen is group 5 and therefore must have 5 valence electrons. So for 2 nitrogen atoms there would be 10 valence electrons altogether.
By the octet rule, there must be 8 electrons for each atom.


[![1st image](https://i.stack.imgur.com/vpJpH.png)](https://i.stack.imgur.com/vpJpH.png)


So right now in the image above, each nitrogen atom is bonded to 2 valence electrons(bond is equal to 2 electrons being paired )
[![enter image description here](https://i.stack.imgur.com/Riy9C.png)](https://i.stack.imgur.com/Riy9C.png)


Now I have added the 6 valence electrons to the nitrogen atom on the right so that it complies with the octet rule of having 8 valence electrons. If you were to count the number of valence electrons overall it would be 8. But we should have 10 valence electrons. So, I have added this onto the nitrogen atom on the left in the image below.[![enter image description here](https://i.stack.imgur.com/kYTWR.png)](https://i.stack.imgur.com/kYTWR.png)


Although the nitrogen atom on the right has 8 valence electrons and complies with the octet rule, the nitrogen atom on the left does not as it only contains 4 valence electrons. To solve this problem, you would want to share more valence electrons with the left nitrogen atom. This would mean converting 2 valence electrons into a bond. THis has been illustrate in the next two images.
[![enter image description here](https://i.stack.imgur.com/GZ2Ln.png)](https://i.stack.imgur.com/GZ2Ln.png)


[![enter image description here](https://i.stack.imgur.com/IM6YR.png)](https://i.stack.imgur.com/IM6YR.png)


If you were to now count the number of valence electrons in each nitrogen atom, they would both equal 8. If you were to do some research on formal charge for the most ideal shape, this would be 0 and so is the ideal structure.


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