Atomic Element Z = 53 • Halogen

Iodine (I) — Atomic Data, Electron Shells & Reactions

Iodine (symbol I, atomic number 53) has a standard atomic weight of 126.9 u and ground-state configuration [Kr] 4d10 5s2 5p5.

← 52 Te Full Atlas 54 Xe →

IUPAC Physical & Atomic Properties

Atomic Number (Z) 53 IUPAC Symbol I Standard Atomic Weight 126.9 g/mol Period / Group / Block 5 / 17 / p-block Condensed Electron Config [Kr] 4d10 5s2 5p5 Full Subshell Config 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p5 Principal Shell Occupancy [2, 8, 18, 18, 7] Pauling Electronegativity 2.66 First Ionization Energy 1008 kJ/mol Covalent Radius 139 pm Melting Point 386.85 K (113.70 °C) Boiling Point 457.4 K (184.25 °C) Density 4.93 g/cm³ Oxidation States +7, +5, +1, -1

Bohr Shell Diagram & Balanced Reactions

I (Z=53) — Valence shell highlighted in vermilion

Interactive Stoichiometry Reactions Involving Iodine:

Pb(NO3)2 + KI -> PbI2 + KNO3 I2 + Na2S2O3 -> NaI + Na2S4O6