How to draw Lewis structure of molecules with N

In summary, the conversation discusses difficulties in drawing correct Lewis structures for molecules with nitrogen. The example of H2CNN is given, where the initial assumption of a double bond between C and N and a single bond between N and N is incorrect. The correct structure involves transforming the lone pair of the central atom into a bond between the two nitrogens. More examples of similar problems are requested for further practice.
  • #1
tinir
5
0
Many times, I find it hard to draw correct Lewis structure of molecules with nitrogen. For instance: the Lewis structure of H2CNN. I thought it should be double bond between C and N and single bond between N and N, like this:
Photo on 3-17-13 at 1.54 PM_meitu_1.jpg

But actually it's not. I have done many problems like this wrong.

Please help me out! Thx!
 
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  • #2
That's certainly a correct Lewis structure for this molecule. However, when viewed at as a representation of a valence bond structure, it may not be a structure with high importance.
The point is that the rightmost nitrogen has only a sextet. Transforming the lone pair of the central atom into a bond between the two nitrogens will lead to a structure fulfilling the octet rule on all atoms.
 
  • #3
Thank you so much! It helps me a lot!
 
  • #4
Could you give some more examples (just the molecular formula, not necessarily your attempts) of problems like this (since as you say you've tried several of them)? Because I originally did not get this one straight away and would love to work on a few more :)
 
  • #5
OK, I will reply to you when I find those problems. I could not remember where exactly are they.
 

FAQ: How to draw Lewis structure of molecules with N

How do I determine the number of valence electrons for nitrogen in a Lewis structure?

The number of valence electrons for an atom in a Lewis structure is equal to the number of electrons in its outermost energy level, also known as the valence shell. For nitrogen, this number is 5.

2. What is the general rule for drawing Lewis structures of molecules with nitrogen?

The general rule for drawing Lewis structures is to start by arranging the atoms in a molecule, connecting them with single bonds. Then, distribute the valence electrons around the atoms in order to fulfill the octet rule, which states that most atoms tend to form bonds in order to have 8 electrons in their outermost energy level. For nitrogen, this means it will typically form 3 covalent bonds and have one lone pair of electrons.

3. How do I know when to use a double or triple bond when drawing a Lewis structure with nitrogen?

In some cases, atoms such as nitrogen may need to form double or triple bonds in order to fulfill the octet rule. This is especially true for molecules with elements from the third period of the periodic table and beyond. To determine when to use double or triple bonds, count the number of valence electrons in the molecule and distribute them accordingly, keeping in mind that each bond consists of 2 electrons.

4. Can a Lewis structure with nitrogen have an incomplete octet?

While most atoms in a Lewis structure strive for a complete octet, there are some exceptions, including nitrogen. In certain molecules, nitrogen may have an incomplete octet, meaning it does not have 8 electrons in its outermost energy level. This is common in molecules such as nitric oxide (NO) or nitrogen dioxide (NO2).

5. Is there a specific order in which the atoms should be arranged in a Lewis structure with nitrogen?

Typically, the most electronegative atom in a molecule is placed in the center, with the other atoms surrounding it. This helps to minimize the formal charges on each atom, making the Lewis structure more stable. For nitrogen-containing molecules, nitrogen is usually placed in the center, unless it is bonded to a more electronegative atom such as oxygen or fluorine.

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