[chlowoform]

In class today we had to name the compound BO_3. The answer was boron trioxide. I am confused because I thought the charges had to balance (i.e. B has a +3 and O_3 has a -6 charge; I thought boron trioxide would have to be B_2O_3). I asked the prof and she told me charges don't matter when naming this kind of compound.

When do charges matter in naming compounds? When don't they matter?

[Borek]

You were not asked to predict the formula (then your approach would be perfectly OK) bot to name a given compound (poorly chosen if you ask me, I prefer using formulas of existing compounds).