Iodine

Iodine is a chemical element with the symbol I and atomic number 53. The heaviest of the stable halogens, it exists as a semi-lustrous, non-metallic solid at standard conditions that melts to form a deep violet liquid at 114 degrees Celsius, and boils to a violet gas at 184 degrees Celsius.

What the numbers say

At standard temperature and pressure Iodine is a solid, sitting in period 5, group 17 of the p-block.

Its melting point of 387 K (114 °C) is the 88th highest of the 110 elements with a measured value — mid-range among the elements.

At 4.94 g/cm³ it is the 64th densest of 96 elements with a quoted density.

Pauling electronegativity is 2.66. Paired with oxygen (3.44) that is a difference of 0.78, which puts the bond polar covalent — oxides here tend to be semiconducting or refractory rather than salt-like.

In the solid state it takes a base orthorhombic structure.

It is reported in 6 oxidation states (-1, 1, 3, 4, 5, 7), which sets how many distinct compounds and phases it can form.

First identified in 1811.

Crystal structure

Check it against computed structures

The structure search queries the Materials Project, OQMD and the Open Materials Database for computed crystal structures containing I — with DFT formation energy, hull stability and band gap where the provider publishes them.