Posted by **candy** on Thursday, April 2, 2009 at 5:10am.

When drawing the 'dot and cross' diagram to show the ionic bonding in aluminium oxide, Al2O3, do we place the nos "2" and "3" in front of the brackets containing the 'dot and cross' diagram, e.g 2[Al]3[O]?

I notice that some books place the "2" and "3" as subscripts while others place the nos. in front.

- Chemistry -
**SraJMcGin**, Thursday, April 2, 2009 at 10:04am
Since this is definitely not my field, try the following:

http://www.google.com/search?q=numbers+2+and+3+in+a+dot+and+cross+diagram&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a

If you see them in more than one position, it may be that either is acceptable.

Sra

- Chemistry -
**DrBob222**, Thursday, April 2, 2009 at 11:39am
The link provided by SraJMcGin refers more to the cross product of mathematics than to your question.

What you want to do with ionic compounds is to show

2Al^{+3} + O^{-2} with two pairs of electrons on the left, top, right, and bottom of the O. I can't draw them on the board. The other way of doing it is to show one Al ion with another just below it, then to the right show 3 O atoms, one above the other, and put in the dots and crosses on the O. Don't forget to put the -2 charge on each oxygen when you have finished.

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