Here's why:

* Structure: Iodine exists as diatomic molecules (I₂). These molecules are held together by weak van der Waals forces in the crystal lattice.

* Bonding: The bond within the I₂ molecule is a covalent bond, where electrons are shared between the two iodine atoms. This is a strong bond.

* Properties: Molecular crystals are generally soft, have low melting points, and are poor conductors of heat and electricity. These characteristics are consistent with iodine's properties.

In contrast, ionic crystals are formed by electrostatic attractions between oppositely charged ions. They tend to be hard, have high melting points, and conduct electricity when molten or dissolved.

Therefore, the weak intermolecular forces holding I₂ molecules together in the solid state classify iodine crystal as a molecular crystal.