53I126.90
Iodine (I)
Element 53 · Halogen
Iodine (I) is a chemical element with atomic number 53. It is classified as a halogen in period 5, group 17 of the periodic table (the p-block). Its standard atomic weight is 126.90 u and its ground-state electron configuration is [Kr] 4d¹⁰ 5s² 5p⁵.
Iodine facts
| Atomic number (Z) | 53 |
|---|---|
| Symbol | I |
| Standard atomic weight | 126.90 u |
| Category | Halogen |
| Group | 17 |
| Period | 5 |
| Block | p-block |
| Electron configuration | [Kr] 4d¹⁰ 5s² 5p⁵ |
| Electronegativity (Pauling) | 2.66 |
| State at 20 °C | Solid |
| Protons / electrons | 53 / 53 |
| Neutrons (most common isotope, approx.) | 74 |
| Molar mass | 126.9 g/mol |