Chemistry gcse help, about ammonia/ammonium/methane?

Ammonia, NH3, is a smelly gas, and is an uncharged compound. Ammonium, (NH4)+, is an ion, and is only found combined with negative ions such as chloride, Cl-, as in ammonium chloride, NH4Cl. Methane, CH4, is an uncharged compound found in natural gas. There is no CH3 at all.

I don't do A level Physics and Chemistry but a lot of my friends do and they find it very hard (and they are all extremely clever). There is never a moment when they don't complain about it. Apparently, everything you've learnt in Chemistry so far is a lie and you have to learn things like the structure of an atom all over again with a lot of new, complicated information. But if you feel confident in those two subjects at the minute I recommend you do them for A Level. It is far from impossible to do, so don't be put off by what I've said. Out of interest, how do you know you have As at GCSE? Surely you've just done your exams so you won't have your results yet? ETA: Oh yes, that makes sense. I think I did that... Appalling memory, apologies.