53 2 · 8 · 18 · 18 · 7

Iodine, I, element 53

Halogen· Period 5· Group 17· p-block

Configuration [Kr]4d105s25p5

Atomic weight
126.904Da
Phase
solid
Density
4.933g/cm³
Melting point
386.85K 113.7 °C
Boiling point
457.55K 184.4 °C
Electronegativity
2.66

Dark violet nonmetallic element, belongs to group 17 of the periodic table. Insoluble in water. Required as a trace element for living organisms. One stable isotope, I-127 exists, in addition to fourteen radioactive isotopes. Chemically the least reactive of the halogens, and the most electropositive metallic halogen. Discovered in 1812 by Courtois. Description from mendeleev.

Back to the table
The outermost shell: the valence electronsThe inner shellsThe nucleus One bead for each electron, on the ring of its shell, counted from the nucleus out. The rings turn at their own pace; the model is Bohr's picture of the atom, which places electrons in shells but not on true orbits.

Atomic properties

5 of 5 fields have a value for iodine

Atomic weight The standard atomic weight. For an element with no stable isotope, the mass of its longest-lived isotope.
126.9045Da
Source: mendeleev
Electron configuration
[Kr]4d105s25p5
Source: mendeleev
Uncertainty of the atomic weight
3×10−5Da
Source: mendeleev
Electron configuration in full The electron configuration with the noble-gas core written out.
1s22s22p63s23p63d104s24p64d105s25p5
Source: Worked outfrom electron configuration
Electrons in each shell Counted from the electron configuration, from the first shell outward.
2 · 8 · 18 · 18 · 7
Source: Worked outfrom electron configuration

Screening of each subshell

Clementi's screening constants: how much of the nucleus's charge the other electrons hide from an electron in each subshell. What is left is the effective nuclear charge it feels.

SubshellScreening σEffective charge Z − σ
1s1.060951.9391
2s13.93339.067
2p4.152648.8474
3s18.212634.7874
3p18.158634.8414
3d14.099338.9007
4s27.702825.2972
4p28.970424.0296
4d32.06620.934
5s39.596513.4035
5p41.388511.6115