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.
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:
So, I am trying to figureout the ratio of calcium to oxalate I should combine in a meal to produce the binding of calciumoxalate in the gut instead of the kidney
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