Crystal Lattice

In table salt, sodium and chlorine take turns in rows of little cubes. Diamond and graphite are both pure carbon: in diamond each atom holds on to four others, which makes it very hard, while graphite's flat sheets slide apart, which is why a pencil writes.

Tap it to send a wave through it: a ripple runs across, each slice of atoms rising and falling in turn, the bonds between them stretching and bending. Sound and heat travel through solids as waves like this. In ice, the water molecules spread out into an open pattern, so ice floats on water. Metals, quartz and graphene are in the Splash tab too.