Element 53
Iodine
Halogens
Iodine (I) is in the p-block of the periodic table — group 17, period 5.
Iodine is a chemical element with symbol I and atomic number 53.
Key data
- Atomic number
- 53
- Atomic mass
- 126.904 u
- Group / Period
- 17 / 5
- Block
- p-block
- Phase at STP
- Solid
- Density
- 4.933 g/cm³
- Melting point
- 113.7 °C
- Boiling point
- 184.3 °C
- Electron configuration
- [Kr] 4d10 5s2 5p5
Periodic table block
Iodine is in the p-block (group 17, period 5). Elements land in the p-block when their highest-energy electrons fill a p subshell — this region holds most nonmetals, the metalloids, and the metals on the right of the table.
New to this? Periodic table blocks explained: s, p, d, and f
Common uses
- •Antiseptics
- •Thyroid hormone
- •Iodized salt
Discovery
Year: 1811
Discovered by: Bernard Courtois
Frequently asked questions
What is the atomic number of Iodine?
Iodine has atomic number 53. Its symbol is I and its atomic mass is 126.904 u.
What category of element is Iodine?
Iodine is classified as halogens. It sits in group 17, period 5 of the periodic table.
What block of the periodic table is Iodine in?
Iodine is in the p-block (group 17, period 5). Its highest-energy electrons occupy the p subshell — you can see this in its electron configuration, [Kr] 4d10 5s2 5p5.
What is Iodine used for?
Common uses of Iodine include: Antiseptics, Thyroid hormone, Iodized salt.
When was Iodine discovered?
Iodine was discovered in 1811 by Bernard Courtois.
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