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 and #4, #5, #6 and #7.

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

Let us consider the case of
IO

_{3}^{-}_{ }:__Step 1__: The central atom will be the I atom since it is the less electronegative. Connect the atoms 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 4 since
IO

_{3}^{-}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**IO_{3}^{-}_{ }__Step 3 & 4__: Therefore, the Lewis structures for IO_{3}^{-}are as follows:Figure 1: Lewis
structures for IO_{3}^{-}. The iodine atom is not restricted
to an octet. Double bonds may be generated from the oxygen lone pairs so that
to minimize charge separation. |

Which is more stable lewis structure?

ReplyDeleteThe iodine atom is not restricted to an octet. This is true also for elements higher than period 2 of the periodic table. Structures 1, 2 and 3 are of equal stability since they are resonance structures and they all have the same charge separation.

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