Lewis Electron Dot Structures - Simple Procedure for writing Lewis Structures – Lewis Structures for methanimine (CH2NH) - Example #25

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, #19, #20, #21, #22,  #23 and #24.

Let us consider the case of  methanimine, CH₂NH . Methanimine can form the simplest aminoacid, glycine, when it reacts with either hydrogen cyanide and then with water, or formic acid. It has been detected even in other galaxies like Arp220 in 2008.

 

Step 1: Connect the atoms with single bonds. The central atom is the carbon atom.

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

Where n in this case is 5 since CH₂NH consists of five atoms.

Where V = (1 + 1 + 4 + 5 + 1 ) = 12  

Therefore, P = 6n + 2 – V = 6 *2 + 2 – 12 = 2   Therefore,  there is one double bond and the structure in Step 1 is has one double bond.

 

Step 3 & 4: The Lewis structure for CH₂NH is as follows:

Figure 1: Lewis structure for methanimine.

Lewis Electron Dot Structures - Simple Procedure for writing Lewis Structures – Lewis Structures for the bromate ion (BrO3-) - Example #24

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, #19, #20, #21 , #22 and  #23.

Let us consider the case of  BrO₃^-. Bromates are formed by many different ways in municipal drinking water, The most common is the reaction of Br^- with ozone:

                                                           Br^-  + O₃ →   BrO₃^-

In waters containing bromide (Br^-), such as those found in coastal regions subject to salt water intrusion, a disinfection by-product of the ozonation treatment of the water is the bromate ion BrO₃^-.
 The bromate ion is very carcinogenic with an estimated lifetime cancer risk 1:10000 for a concentration of 5 ppb. Several methods are used for the determination of bromate in drinking waters including an LC-ICP-MS method.
 

Step 1: Connect the atoms with single bonds. The central atom is the bromine atom.

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

Where n in this case is 4 since BrO₃^- consists of four atoms.

Where V = (7 + 6 + 6 + 6 ) – (-1) = 26  

Therefore, P = 6n + 2 – V = 6 *4 + 2 – 26 = 0     So, there are no π electrons in BrO₃^- and the structure in Step 1 is the Lewis structure. However, let us see the charge on the atoms.

Step 3 & 4: The Lewis structure for BrO₃^-  including charge is as follows:

Figure 1: Lewis structures for BrO₃^- . Structure 3 has the most reasonable distribution of formal charges.

Lewis Electron Dot Structures - Simple Procedure for writing Lewis Structures – Lewis Structures for Dinitrogen Trioxide (N2O3) - Example #23

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, #19, #20, #21 and #22.

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

Let us consider the case of dinitrogen trioxide (N₂O₃).
 

Step 1: Connect the atoms with single bonds. The central atoms are the nitrogen atoms.

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

Where n in this case is 5 since N₂O₃ consists of five atoms.

Where V = (5 + 5 + 6 + 6 + 6 ) = 28  

Therefore, P = 6n + 2 – V = 6 *5 + 2 – 28 = 4  Therefore, there are 4π electrons in N₂O₃ and 2 double bonds or a triple bond must be added to the structure in Step 1.

Step 3 & 4: The Lewis structure for N₂O₃  is as follows:

Figure 1: Lewis structure for N₂O₃

Lewis Electron Dot Structures - Simple Procedure for writing Lewis Structures – Lewis Structures for Dinitrogen Tetroxide (N2O4) - Example #22

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, #19, #20 and #21.

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

Let us consider the case of dinitrogen tetroxide (N₂O₄).
 

Step 1: Connect the atoms with single bonds. The central atoms are the nitrogen atoms.

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

Where n in this case is 6 since N₂O₂ consists of six atoms.

Where V = (6 + 5 + 5 + 6 + 6 + 6 ) = 34  

Therefore, P = 6n + 2 – V = 6 * 6 + 2 – 34 = 4     There are 4π electrons in N₂O₄ and that means 2 double bonds or a triple bond must be added to the structure in Step 1.

However, all the atoms present are second row elements and cannot accommodate more than 8 valence electrons. Therefore, a triple bond cannot be used as it would place ten electrons around the atoms bonded. The only possible case is that of two double bonds.

 

Step 3 & 4: The Lewis structure for N₂O₄  is as follows:

Figure 1: Lewis electron dot structures for N2O4

Lewis Electron Dot Structures - Simple Procedure for writing Lewis Structures – Lewis Structures for Dinitrogen Dioxide (N2O2) - Example #21

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, #19 and #20.

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

Let us consider the case of dinitrogen dioxide (N₂O₂). Dinitrogen dioxide is the brown film we see in the atmosphere all over highly polluted cities.

 Step 1: Connect the atoms with single bonds. The central atoms are the nitrogen atoms.

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

Where n in this case is 4 since N₂O₂ consists of four atoms.

Where V = (5 + 5 + 6 + 6 ) = 22  

Therefore, P = 6n + 2 – V = 6 * 4 + 2 – 22 = 4   So there are 4π electrons in N₂O₂ 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 N₂O₂  is as follows:

Figure 1: Lewis structures for N₂O₂. Structure #1 is the only experimentally observed structure. Structure #4 is the least plausible since O the most electronegative of the elements in the above structure has a + charge and N the least electronegative of the atoms present a – charge.

Lewis Electron Dot Structures - Simple Procedure for writing Lewis Structures – Lewis Structures for Carbon Disufide (CS2) - Example #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:

Figure 1: Plausible Lewis structures for carbon disulfide

Lewis Electron Dot Structures - Simple Procedure for writing Lewis Structures – Lewis Structures for Chlorine Dioxide (ClO2) - Example #19

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 and #18.

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

Let us consider the case of chlorine dioxide (ClO₂). Chlorine dioxide is used mainly for bleaching of wood pulp, for bleaching of flour and for the disinfection of municipal drinking water:

 Step 1: Connect the atoms with single bonds. Chlorine is the central atom.

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 since ClO₂ consists of three atoms.

Where V = (6 + 6 + 7 ) = 19  

Therefore, P = 6n + 2 – V = 6 * 3 + 2 – 19 = 1   So there is only 1 π electron in ClO₂ 

So the structure of Step 1 is the Lewis structure.

Electrons are placed around each atom so that the octet rule is obeyed. Since the number of valence electrons is odd the octet rule will not be obeyed in all the atoms.

Formal charges are assigned and equalized using resonance.

 

Step 3 & 4: The Lewis structure for ClO₂  is as follows:

Figure 1: Plausible Lewis structures for chlorine dioxide. Oxygen is more electronegative than chlorine so it can accommodate better the negative charge. Structure 3 has no formal charge.   The real molecule is a hybrid of the above Lewis structures