I think the trouble is that the time scale you've assumed for molecular reactions is off; atoms move and react much faster than you may expect. (In air at room

I think the trouble is that the time scale you've assumed for molecular reactions is off; atoms move and react much faster than you may expect. (In air at room temperature, an individual molecule will undergo billions(?) of collisions per second.) The atoms and molecules in this video are moving on the order of 200 m/s, and the image is only about 5 nm wide. To see atoms slowly forming together, you need to watch on the scale of picoseconds at a time, not the 20 ms - 40 ms per frame in this video. A molecular dynamics simulation might give a better impression of the time scale: https://www.youtube.com/watch?v=FK29kxMSqH8&t=2m45s https://www.youtube.com/watch?v=FK29kxMSqH8&t=2m45s. (I'm not sure what volume is being simulated there. It's much larger than what's seen in the submission, which is about 18 water molecules wide if we assume water molecule size of 0.27 nm.) Note the time scale on the left. The whole simulation is 250 ps, so you have to watch it about 100 million times to match a single frame in the submission's video.