Lewis Dot Structures|How to draw Lewis Structure – Lewis structures of Cyanamide NCN-2

Lewis Dot Structures of the Cyanamide ion NCN^-2

A simple procedure for writing Lewis Dot Structures was given in a previous post entitled “Lewis Structures and the Octet Rule”. Several worked examples relevant to this procedure were given in previous posts please see the Sitemap - Table of Contents (Lewis Electron Dot Structures).

Let us consider the case of the NCN^-2 ion and draw the Lewis dot structures:

Step 1: Connect the atoms with single bonds.

 

Step 2: Calculate the # of electrons in ð bonds (multiple bonds) using formula (1):

Where n in this case is 3 since NCN^-2consists of  3 atoms.

Where V = 5 + 4 + 5 – (-2) = 16

Therefore, P = 6n + 2 – V = 6 *3 + 2 – 16 = 4   Therefore, there are either 2 double bonds or 1 triple  bond.

Step 3 & 4: The Lewis structures of of NCN^-2 are as follows:

 

The ion represented by the electron dot structure #1 is the most stable comparing to the #2 and #3 because of less charge separation. The cyanamide ion is isoelectronic and hence isostructural with the CO₂ molecule. 

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Relevant Posts

Lewis Structures|Octet Rule: A Simple Method to write Lewis Structures

Canonical Structures - Lewis Dot Structure of OCN-

 

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References

1. G.N. Lewis, J.A.C.S, 38, 762-785, (1916)
2. E. C. McGoran, J. Chem. Educ., 68, 19-23 (1991)
3. A.B.P. Lever, J. Chem. Educ., 49, 819-821, (1972)

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Key Terms

resonance structures of cyanate ion NCN-2, Lewis electron structures of cyanamide ion, chemical formula of the cyanamide, simple procedure for drawing Lewis structures of cyanamide ion,

 

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