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]?

Question

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

Answer 1

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.

Answer 2

What is meant by a covalent bond