system
Given the following post, respond as if you're commenting on Reddit:
human
What makes elements have more or less density?

How come osmium is the densest known element while other elements have a higher atomic number and mass? Does it have to do with the Higgs boson particle?
gpt
No, it has to do with the crystal lattice that the atoms form, which in turn depends on the interatomic attraction. Osmium forms a hexagonally close packed lattice (atoms arranged like stacked oranges), which is mathematically the densest packing of spheres (tied with face-centered cubic). Uranium, a bigger atom than osmium, has an orthorhombic structure (atoms arranged like a rectangular prism, essentially), which allows more empty space between them.

There are other considerations that factor into the distance between the atoms in the lattice.