Iodine (I) - Element 53 | Properties & Electron Configuration
What is Iodine?
Iodine (I) is element 53, a halogen in period 5, group 17. Its electron configuration is 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁵.
| Atomic Number | 53 |
| Symbol | I |
| Atomic Mass | 126.9 u |
| Category | Halogen |
| Period | 5 |
| Group | 17 |
| Block | p |
| Electron Configuration | 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁵ |
| Short Config | [Kr] 4d¹⁰ 5s² 5p⁵ |
| Electronegativity | 2.66 |
| Atomic Radius | 133 pm |
| Ionization Energy | 1008 kJ/mol |
| Electron Affinity | 295 kJ/mol |
| Phase (STP) | Solid |
Electron Configuration
The full electron configuration of Iodine is 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁵. In noble gas shorthand, this is written as [Kr] 4d¹⁰ 5s² 5p⁵.
Iodine is a p-block element in group 17, period 5.
Periodic Trends
Electronegativity: Iodine has a Pauling electronegativity of 2.66. Within group 17, electronegativity generally decreases down the group.
Atomic Radius: 133 pm. Across period 5, atomic radius generally decreases left to right as nuclear charge increases.
Ionization Energy: 1008 kJ/mol. Ionization energy generally increases across a period and decreases down a group.
View all 118 elements with trend overlays for electronegativity, atomic radius, ionization energy, and electron affinity.
Explore Iodine on the Interactive Periodic TableRelated Topics
Fluorine (F)
Properties of Fluorine - same group as Iodine
Chlorine (Cl)
Properties of Chlorine - same group as Iodine
Bromine (Br)
Properties of Bromine - same group as Iodine
Rubidium (Rb)
Properties of Rubidium - same period as Iodine
Strontium (Sr)
Properties of Strontium - same period as Iodine
Yttrium (Y)
Properties of Yttrium - same period as Iodine