* Basic Unit: Iodine exists as diatomic molecules (I₂), meaning two iodine atoms are covalently bonded together.

* Layered Arrangement: These I₂ molecules arrange themselves in a layered structure, held together by van der Waals forces. These forces are relatively weak, which explains why iodine has a low melting point.

* Within Layers: The I₂ molecules within a layer are closely packed, leading to strong interactions between them.

* Between Layers: The interactions between layers are weaker, allowing them to slide past each other relatively easily. This explains iodine's characteristic shiny, flaky appearance.

In Summary: Solid iodine's structure is a layered arrangement of diatomic I₂ molecules held together by weak van der Waals forces.