This site tells lies. I'm trying to post less than 2000 characters at a time, I've had the text editor count them.
What an interesting thread and I've missed it so far. I'm not a scientist, but as someone who avidly looks for the popular science in the media, I can give you my opinion/understanding.
I think you need to avoid considering this "a chemical question". Until there is enough matter to form elements in quantity, chemistry can't really apply.
There even seems to be some disagreement whether the big bang is the start or whether there is a cycle of such things, or whether new universes are created from an existing one. It's all very front line stuff. But a popular theory seems to be that there was no before. So, asking where it all came from becomes invalid, there was no existence before. Matter, space, and time all came into existence in this universe together. To ask what was before the start is a bit like asking what's north of the north pole.
The concept of things springing into existence from nowhere may seem difficult to accept, but there seems to be something similar happening in outer space. Admittedly in space, by definition we already have space :-) but particles and anti-particles come into existence all the time, then after a while meet up and annihilate each other.