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 examine the case of phosphorous oxychloride POCl3. How can we
construct the POCl3 resonance Lewis dot structure?
Step 1: Connect the atoms with
single bonds. The less electronegative is the phosphorous atom. Hence, the P
atom is going to be the central atom. Recall that electronegativity decreases as we move away from the fluorine atom in the periodic chart.
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Fig.1: Connect the atoms of the POCl3
molecule with single bonds
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Step 2: Calculate the # of electrons in π bonds (multiple bonds) using formula (1):
Where n in this
case is 5. Where V = (7 +5 + 7 + 6 + 7 )
= 32 , V is the number of valence electrons of the POCl3.molecule.
Therefore, P = 6n
+ 2 – V = 6 * 5 + 2 – 32 = 0 So, there is no double bond.
Step 3 & 4: The resonance Lewis electron dot structures of POCl3 are as follows:
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| Fig. 2 : Electron dot structures of POCl3 |
Please, watch the following video on how to draw Lewis structures:
I think Figure 2 has two more electrons than it should. Remove a lone pair on the oxygen.
ReplyDeleteThank you David! It is a typo. Oxygen is allowed to have a max. of 8 electrons! A lone pair must be removed
DeleteIn the case of POCl3, the Lewis structure offers not only a window into its atomic arrangement but also into its functional capacities in diverse scientific arenas.
ReplyDelete