Simple Procedure for writing Lewis Structures of allene C3H4 -Ex. #14

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 and #13.

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

Let us consider the case of allene (C₃H₄). Allenes have proven themselves to be valuable building blocks toward complex molecular targets, revealing novel applications in natural product synthesis, pharmaceutical chemistry and material science. The ongoing interest in allene chemistry results in a variety of new methodologies and pathways for the synthesis of allenes.

Step 1: Connect the atoms with single bonds

Fig. 1: Connecting the allene atoms with single bonds (step 1)

Step 2: Calculate the # of electrons in π bonds (multiple bonds) using  formula (1) in the article entitled “Lewis Structures and the Octet Rule”.:

Where n in this case is 3 (exclude the H atoms)

Where V = (4 + 2 + 4 + 4+ 2) = 16  

Therefore, P = 6n + 2 – V = 6 * 3 + 2 – 16 = 4   So there are 4 π electrons in  C₃H_{4 .}  Therefore, 2 double bonds or 1 triple bond must be added to the structure of Step 1.

  

Step 3 & 4: The Lewis structures for C₃H₄ are as follows:

Fig. 2: Lewis electron dot structure for the allene molecule C₃H₄

Simple Procedure for drawing Lewis Structures for the Azide ion N3- -#13

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 and #11. 

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

 Let us consider the case of azide ion (N₃^-). Azides are energy-rich molecules with many applications. Sodium azide (NaN₃), for example, is used as a preservative, mutagen, biocide and assay reagent. It has also been used as a component in the gas generators used to inflate certain automotive airbag safety systems, providing the source of nitrogen gas necessary to inflate the bag instantaneously. Organic azides are capable of a great diversity of organic reactions and are important components in Click Chemistry.

Step 1: Connect the atoms with single bonds

Fig. 1: Connecting the N atoms of the azide ion with single bonds according to step 1 of the method

Step 2: Calculate the # of electrons in π bonds (pi bonds, multiple bonds) using  formula (1) in the article entitled “Lewis Structures and the Octet Rule”.:

Where n in this case is 3 since N₃^- consists of three atoms.

Where V = (5 + 5 + 5) – (-1) = 16  

Therefore, P = 6n + 2 – V = 6 * 3 + 2 – 16 = 4    Therefore,  there are 4 π electrons (pi electrons) in N₃^-

and that means that 2 double bonds or 1 triple bond must be added to the structure of Step 1.
 Step 3 & 4: The Lewis structures for N₃^- are as follows:

Figure 2: Lewis structures for N₃^- _.  Structure 1 is the most plausible since it has the smallest charge separation .

Simple Method for writing Lewis Structures of the Oxalate ion C2O4-2 -#12

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 and #11. 

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

 Let us consider the case of oxalate ion (C₂O₄^-2). Oxalate is a dianion that forms coordination compounds acting as a ligand. Many metal ions form insoluble precipitates with oxalate, a prominent example is calcium oxalate, a primary constituent of kidney stones.  

 

Step 1: Connect the atoms with single bonds

Fig. 1: Connecting the atoms of the oxalate ion C₂O₄^-2 with single bonds

Step 2: Calculate the # of electrons in π bonds (multiple bonds) using  formula (1) in the article entitled “Lewis Structures and the Octet Rule”. 

:

Where n in this case is 6 since  C₂O₄^-2  consists of six atoms.

Where V = (4 + 6 + 6 + 4 + 6 |+ 6) – (-2) = 34  

Therefore, P = 6n + 2 – V = 6 * 6 + 2 – 34 = 4   \  there are 4 π electrons in C₂O₄^-2   \

2 double bonds or 1 triple bond must be added to the structure of Step 1.

Step 3 & 4: The Lewis structures for C₂O₄^-2 are as follows: