53 I Iodine 126.9
Halogen
Iodine 碘
[Kr] 4d¹⁰ 5s² 5p⁵
- Period 5
- Group 17
- Block p
- Solid
Electron configuration
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁵
Orbital diagram (valence)
5s ↑↓
5p ↑↓↑↓↑
- Electrons per shell
- 2, 8, 18, 18, 7
- Unpaired electrons
- 1
- Zeff (Slater)
- 7.60
Properties
- Atomic weight
- 126.9
- Electronegativity (Pauling)
- 2.66
- First ionization energy
- 1008 kJ/mol
- Electron affinity
- 295.1 kJ/mol
- Covalent radius
- 139 pm
- van der Waals radius
- 198 pm
- Melting point
- 386.9 K
- Boiling point
- 457.6 K
- Density
- 4.93 g/cm³
- Melting / boiling point
- 113.7 °C / 184.4 °C
- Common oxidation states
- +7, +5, +1, −1
- Discovered
- 1811
Iodine in the course
The lessons that discuss this element most (ranked by mentions).
- Halogens and noble gases The main-group elements
- Reaction rates and rate laws Reaction rates
- Coulometry: counting electrons, counting water Electroanalytical chemistry
- Extraction: partition equilibria and the separating funnel Separations and chromatography
- Reaction mechanisms Reaction rates
- Redox titrations Titrimetric and gravimetric analysis
- Dissolved oxygen: the Winkler titration and the Clark electrode Electroanalytical chemistry
- The equilibrium constant and the reaction quotient Chemical equilibrium
Lab experiments with Iodine
Periodic trend
Group 17
Data: PubChem periodic table (public domain); atomic weights are IUPAC abridged standard values; covalent radii from Cordero et al. (2008).