[ptryon]

Hello

I have attached two short excerpts from a physical chemistry textbook. I have a few questions:

If v is the sum of the numbers of each type of ion in the formula why is v = 2 for MO₂ (rather than 3) and v = 3 for M₂O₂ (rather than 4). Furthermore, why is M₂O₂ not simply MO (afterall we are describing an ionic lattice rather than a simple molecular commpound).

Any help appreciated