Sodium bond dissociation energies

We note that Cotton and Jenkins (4) in the same paper reported bond dissociation energies for LiOH(g) and KOH(g) which are in reasonable agreement with JANAF values (5) for the enthalpy of formation of these two compounds. Furthermore, bond dissociation data for the alkali metal halides ( ) clearly establish the sodium compound as the least stable within each halide series. The potassium and sodium compounds differ by from 4.3 kcal mol for the fluorides and bromides to 3.6 kcal mol for the chlorides. 

Fig 3 1 The bond between sodium and chlorine is almost purely ionic because the dissociation energy (3) is so much greater than the difference between the ionization potential (1) of sodium and the electron affinity (2) of chlorine. The energies are given in electron volts. 

Since most of the dissociation reaction of an isolated molecule occurs in a very short timescale ( 100 fsec), the direct observation of its transition from reagents to products has to wait until the discovery of femtosecond laser technology. With femtosecond wave packet spectroscopy, the trajectories of particles can be monitored during their motions on a potential energy surface. Zewail s group in 1989, for the first time, directly followed the evolution in space and time of such trajectories during the breakage of a chemical bond in the dissociation of sodium iodide. 

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