Iodine: bond enthalpies in gaseous diatomic species

The bond energy in the gaseous diatomic species II is 151.088 kJ mol-1.

The following values refer to neutral heterodiatomic molecules in the gas phase. These numbers may well differ considerably from, say, single bond energies in a solid. All values are given in kJ mol-1.

Table of diatomic IX bond enthalpies. All values are quoted in kJ mol-1. Each formula in the table (IO, IF, and so on) is a link - select these to see visual periodicity representations for bond enthalpies involving iodine to elements of your choice.

Period 1

IH             IHe
298.407              

Period 2

ILi IBe IB IC IN IO IF INe
345.2 ±4.2   220.5 ±0.8 209 ±21 159 ±17 249.0 ±1.3 < 271.5  

Period 3

INa IMg IAl ISi IP IS ICl IAr
304.2 ±2.1 about 285 369.9 ±2.1 293     211.3 ±0.4 10.0

Period 4

IK ICa IGa IGe IAs ISe IBr IKr
325.1 ±0.8 284.7 ±8.4 339 ±9.6   296.6 ±28.0   179.1 ±0.4  

Period 5

IRb ISr IIn ISn ISb ITe II IXe
318.8 ±21 269.9 ±5.9 331 234 ±42   192 ±4.2 151.088  

Period 6

ICs IBa ITl IPb IBi IPo IAt IRn
337.2 ±2.1 320.8 ±6.3 272 ±8 193 ±4 218.0 ±4.6      

Period 7

IFr IRa            
               

Notes

I am grateful to Professor J.A. Kerr (University of Birmingham, UK) for the provision of the bond strengths of diatomic molecules data.

The values given here are at 298 K. All values are quoted in kJ mol-1. Generally, these data were obtained by spectroscopic or mass spectrometric means. You should consult reference 1 for further details. A note of caution: the strength of, say, the C-H bond in the gaseous diatomic species CH (not an isolable species) is not necessarily, the same as the strength of a C-H bond in, say, methane.

The strongest bond for a diatomic species is that of carbon monoxide, CO (1076.5 ± 0.4 kJ mol-1). The strongest bond for a homonuclear diatomic species is that of dinitrogen, N2 (945.33 ± 0.59 kJ mol-1).

References

  1. J.A. Kerr in CRC Handbook of Chemistry and Physics 1999-2000 : A Ready-Reference Book of Chemical and Physical Data (CRC Handbook of Chemistry and Physics, D.R. Lide, (ed.), CRC Press, Boca Raton, Florida, USA, 81st edition, 2000.

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iodine atomic number