The dichromate ion, Cr2O72-, has neither Cr¬Cr nor
O¬O bonds.
(...

Question

The dichromate ion, Cr2O72-, has neither Cr¬Cr nor 
O¬O bonds. 
(b) How many outer-shell electrons does each Cr atom have 
in your electron-dot structure? What is the likely geometry 
around the Cr atoms?

Accepted Answer

Hey everyone, we're told that there are no manganese to manganese nor oxygen. Oxygen bonds in the manganese seven oxide based on its lewis structure. How many valence electrons does each manganese adam have And what is the geometry of each manganese atom first? Let's go ahead and draw out our Lewis structure. Looking at our manganese, we know that manganese is in our group seven A And since we have two of manganese, we're going to multiply two times seven to get 14 electrons. Next looking at oxygen, we know that oxygen is in our group six. A And since we have seven of oxygen, we're going to multiply six times seven to get 42. In total, we need to have 56 valence electrons in our Lewis structure. So let's go ahead and draw this out. We were told that there would be no manganese to manganese nor oxygen to oxygen bonds. So oxygen will be our central atom and we have to, manganese surrounding it. We will then have three other oxygen's surrounding our manganese. Now to complete the octet, it's of our oxygen, we will add our lone pairs in To complete our 56 valence electrons. So this would be the final Lewis structure for our Manganese seven oxide. Now, to answer our question, we can see that we have 14 valence electrons surrounding our manganese and since we have four charged clouds or four electron groups connected to each manganese. This means that we have A geometry of AX four, which means we have a tetrahedron geometry And these are going to be our final answers. Now, I hope this made sense and let us know if you have any questions.

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