[s3a]

What I mean by this is like O has a charge of - 2 for example.

But to obtain a chemical formula such as H3PO3 (given the name - Phosphorous acid), how would I know to put a subscript of 3 next to the Hydrogen? I initially guessed HPO3 because ous means ide which means the least which means 3 instead of 4 for POsubscript but how do I know the charge of PO3 as a whole when interacting with hydrogen? I would appreciate a mini explanation as well as the correct term for this so that if I still don't get it I could read about it on the internet or in my book.

Any input would be greatly appreciated!
Thanks in advance!

[stewie griffin]

Well the short answer is that you memorize the structure and charges of the polyatomic ions (nitrate, nitrite, sulfate, suflite, carbonate, phospohate, etc). At least that's how I did it in highschool and it worked just fine. A longer and perhaps more insightful answer is below.

[jrd89]

Be careful, I noticed you said that the suffix -ous was an -ide, and that's not the case here.  The -ous indicates that it's an -ite suffix, in this case Phosphite.