Recognised as Chemical element
Iodine
- I
- Z = 53
- halogen
Iodine (I) is element 53, a halogen in period 5 and group 17. Its standard atomic weight is 126.9 Da. Weights follow IUPAC standard atomic weights, 2021 revision.
Identity
SymbolI
Standard atomic weight126.9atomic mass units (Da)
Mass in kilograms2.1072241 × 10^-25
Categoryhalogen
Group17
Period5
Blockp-block
Electrons in a neutral atom53
Neutrons in the most common isotope74≈
Electron configuration
Configuration1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁵ground state, subshells written in order of n
Noble gas shorthand[Kr] 4d¹⁰ 5s² 5p⁵
Electrons per shell2, 8, 18, 18, 7K, L, M and outward
Electrons in the outer shell7
Unpaired electrons1Hund's rule; unpaired electrons make the free atom paramagnetic
Madelung ruleFollowedthe ground state is what the n + l filling order predicts
Quantities
Molar mass126.9 g/mol
Mass of one mole126.9 grams
Atoms in one gram4.7455798 × 10^21
Mass of one atom2.1072241 × 10^-22 g
Keep nerding
Every link below is a page Nerdulator can generate from what it already knows about this value.
Neighbouring elements
The number
Nerdulate something else
Nothing in mind? Surprise me · today’s page