[cogitator]

Should be CO₃^2-

Otherwise known as carbonate ion.

[Hunble]

Is the O3, three atoms of Oxygen? I honestly do not know what O3 is.

Seriously, I do not understand what they are actually measuring.

Carbon dioxide is C0^2, that that is two atoms of Oxygen attached to a single Carbon atom.

[Hunble]

Did the O3 designate that three electrons are missing from the Oxygen atom?