Iodine (I)
Iodum
Iodine (I) is a halogen in period 5, group 17. Its relative atomic mass is 126.9 and the molar mass of the atom is 126.9 g/mol; the molar mass of I₂ is 253.8 g/mol.
Atomic number 53
Atomic mass 126.9
Molar mass 126.9 g/mol I₂: 253.8 g/mol
Category Halogen Solid
Properties of iodine
| Atomic number | 53 |
|---|---|
| Symbol | I |
| Latin name | Iodum |
| Relative atomic mass | 126.9 |
| Molar mass | 126.9 g/mol · I₂: 253.8 g/mol |
| Group, period, block | 17, 5, p |
| Category | Halogen |
| State at 20 °C | Solid |
| Electron configuration | [Kr] 4d¹⁰ 5s² 5p⁵ |
| Electronegativity (Pauling) | 2.66 |
| Atomic radius | 140 pm |
Electron configuration of iodine
Electrons per shell
K2L8M18N18O7
Full notation
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁵
Noble-gas notation
53 protons · 53 electrons[Kr] 4d¹⁰ 5s² 5p⁵
Formula and compounds of iodine
Simple substanceI₂iodineMolar mass of I₂: 253.8 g/mol
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Frequently asked questions
The relative atomic mass of iodine is 126.9, so the molar mass of the atom is 126.9 g/mol; the molar mass of I₂ is 253.8 g/mol.
Full: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁵. Noble-gas notation: [Kr] 4d¹⁰ 5s² 5p⁵.