I
Iodine is an essential trace element required for thyroid hormone production.
Physical Properties
| Atomic Mass | 126.9 u |
| Density | 4.93 g/cm³ |
| Melting Point | 386.85 K |
| Boiling Point | 457.4 K |
| Appearance | Lustrous metallic gray solid, violet gas |
| State at Room Temp | Solid |
Chemical Properties
| Electronegativity | 2.66 (Pauling) |
| 1st Ionization Energy | 1008.4 kJ/mol |
| Electron Affinity | 295.2 kJ/mol |
| Oxidation States | -1, +1, +3, +5, +7 |
Atomic Properties
| Electron Configuration | [Kr] 4d10 5s2 5p5 |
| Atomic Radius | 115.0 pm |
| Covalent Radius | 139.0 pm |
| Van der Waals Radius | 198.0 pm |
Discovery
| Discovered By | Bernard Courtois |
| Discovery Year | 1811 |
| Location | Paris, France |
| Named After | Greek 'iodes' meaning violet |
About Iodine
Iodine is a shiny, purple-black nonmetal that sublimes to a violet gas. It is the heaviest essential element commonly needed by living organisms. Iodine deficiency is the leading preventable cause of intellectual disabilities worldwide.
Uses & Applications
Iodized salt, medical disinfectants, X-ray contrast media, LCD polarizing filters, and pharmaceuticals.
Fun Fact
Iodized salt has prevented millions of cases of intellectual disability -- one of the most successful public health interventions in history.
Isotopes
| Mass Number | Abundance | Half-Life | Stable |
| 127 | 1.0% | - | Yes |
Electron Configuration
[Kr] 4d10 5s2 5p5