2012/02/07

Simple Method for writing Lewis Structures for Carbon Disufide CS2 - Ex.#20

A simple procedure for writing Lewis structures is given in a previous article entitled “Lewis Structures and the Octet Rule”. Relevant worked examples were given in the following articles: Examples #1, #2, #3 , #4, #5, #6,  #7#8, #9, #10, #11, #12, #13, #14#15, #16, #17, #18 and #19.

Another example  for writing Lewis structures following the above procedure is given bellow:

Let us consider the case of carbon disulfide (CS2).

 Step 1: Connect the atoms with single bonds. Carbon is the central atom since it is less electronegative.

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

Where n in this case is 3 since CS2 consists of three atoms.
Where V = (4 + 6 + 6 ) = 16  
Therefore, P = 6n + 2 – V = 6 * 3 + 2 – 16 = 4       So there are 4π electrons in CS2  and that means 2 double bonds or a triple bond must be added to the structure in Step 1.


Step 3 & 4: The Lewis structure for CS2  is as follows:

Plausible Lewis structures for CS2
Figure 1: Plausible Lewis structures for carbon disulfide


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