Iodine (I)
[Kr] 4d¹⁰ 5s² 5p⁵. 1 unpaired electron, period 5, group 17, p block.
Element or ion
Type a symbol, a name or an atomic number, add a charge such as Fe3+ or Cl-, or tap an element in the table. Orbitals fill from m = −l up, spin +½ first.
IIodine, Z = 53, 126.904 u
[Kr] 4d10 5s2 5p5
In full: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁵
- Blockp block
- Period5
- Group17
- Valence7
- Unpaired1
- MagneticPara
Last electron 5p
- n5shell
- l1p subshell
- m0orbital
- s−½spin down
Step by step
- Iodine has 53 electrons.
- Fill in (n + l) order: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁵.
- Write the subshells in order of n: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁵.
- Replace the krypton core with [Kr]: [Kr] 4d¹⁰ 5s² 5p⁵.
Iodine (I): the numbers
| Atomic number | 53 |
|---|---|
| Atomic mass | 126.904 u |
| Period | 5 |
| Group | 17 |
| Block | p block |
| Valence electrons | 7 |
| Unpaired electrons | 1 |
| Magnetic | paramagnetic |
| Last electron | 5p: n = 5, l = 1, m = 0, s = −1/2 |
Iodine (I): quick answers
What is the electronic configuration of iodine?
Iodine has 53 electrons: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁵, or [Kr] 4d¹⁰ 5s² 5p⁵ in short.
How many unpaired electrons does iodine have?
Iodine has 1 unpaired electron, so it is paramagnetic. Put one electron in each box of a subshell before pairing (Hund’s rule) to see them.
What are the quantum numbers of the last electron of iodine?
The last electron goes into 5p: n = 5, l = 1, m = 0, s = −1/2. Orbitals fill from m = −l up, spin +½ first.