Iodine · I Iodine
Essential trace element related to thyroid hormone, also used in contrast materials.
- atomic number / Atomic number
- 53
- atomic weight / Atomic mass
- 126.9045 u
- Family/Group
- 17
- Period · Block / Period · Block
- 5 · p
- Category / Category
- Halogen The · Halogen
- State / State
- solid state
- Electron configuration
- [Kr]5s2 4d10 5p5
- Oxidation states / Oxidation states
- +7, +5, +1, -1
- Electronegativity / Electronegativity
- 2.66（Pauling）
- Density / Density
- 4.93 g/cm³
- Melting point / Melting point
- 386.85 K
- Boiling point / Boiling point
- 457.55 K
- Atomic radius / Atomic radius
- 198 pm（van der Waals）
- First ionization energy
- 10.451 eV
- Discovery year / Discovery
- 1811
attribute description and data source
properties taken from PubChem periodic table snapshot (2026-10-04). Atomic weights may be reference values or representative isotope masses and cannot be considered exact constants for all samples; density, phase transition points, and phase states depend on temperature, pressure, and allotropes. The solidification of helium requires pressure. Some properties of radioactive and superheavy elements are predicted values, and missing items are marked as not included. Please check the original source and experimental conditions for precise calculations.