53
I
126.9
Iodine (I)
Element 53 · Period 5 · Group 17
halogen
solid at room temp
p-block
About Iodine
Essential for thyroid function. Used as antiseptic and in photographic film.
Physical Properties
Atomic Mass
126.9 u
State at 25°C
Solid
Melting Point
113.7 °C
Boiling Point
184.4 °C
Density
4.933 g/cm³
Magnetism
Diamagnetic
Atomic Properties
Electron Configuration
[Kr] 4d¹⁰ 5s² 5p⁵
Electron Shells
2, 8, 18, 18, 7
Electronegativity
2.66
Atomic Radius
115 pm
Ionization Energy
1008 kJ/mol
Oxidation States
-1, +1, +5, +7
Discovery & History
Discovered By
Bernard Courtois
Discovery Year
1811
Named By
Joseph Louis Gay-Lussac
Name origin: Greek: iodes (violet)
Frequently Asked Questions
- Is Iodine a metal, nonmetal, or metalloid?
- Iodine is classified as a halogen.
- What state is Iodine in at room temperature?
- Iodine is a solid at standard room temperature (25°C).
- What is the atomic mass of Iodine?
- Iodine has an atomic mass of 126.9 atomic mass units (u).
- Who discovered Iodine?
- Iodine was discovered by Bernard Courtois in 1811.
- Where is Iodine on the periodic table?
- Iodine is element number 53, located in period 5 and group 17.