Atoms in the universe and our world: discuss the appearance (and formation?) of atoms after the big bang; how many atoms in universe; spatial distribution of atoms
Atoms in industry: role of individual atoms in chemistry, nuclear fusion, fission
Atoms in science: how individual atoms are identified (spectroscopy), investigated (X-ray crystallography) and separated (mass spectrometry, freeze out, diffusion, &c.)—The last has been requested for the chemical element page instead.
Subatomic particle explanations are dated. Should really Fundamental Particles and include a section on the standard model. http://www.particleadventure.org/frameless/startstandard.html would be a good jumping off point—The section wording has been revised.