Silicon: bond enthalpies in gaseous diatomic species

The bond energy in the gaseous diatomic species SiSi is 326.8 ±10.0 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 SiX bond enthalpies. All values are quoted in kJ mol-1. Each formula in the table (SiO, SiF, and so on) is a link - select these to see visual periodicity representations for bond enthalpies involving silicon to elements of your choice.

Period 1

SiH             SiHe
<= 299.2              

Period 2

SiLi SiBe SiB SiC SiN SiO SiF SiNe
    288.3 451.5 470 ±15 799.6 ±13.4 552.7 ±21  

Period 3

SiNa SiMg SiAl SiSi SiP SiS SiCl SiAr
    229.3 ±30.1 326.8 ±10.0 363.6 623 406  

Period 4

SiK SiCa SiGa SiGe SiAs SiSe SiBr SiKr
      301 ±21   548 367.8 ±10.0  

Period 5

SiRb SiSr SiIn SiSn SiSb SiTe SiI SiXe
          452 ±8 293  

Period 6

SiCs SiBa SiTl SiPb SiBi SiPo SiAt SiRn

Period 7

SiFr SiRa            


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).


  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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