Born-Haber cycle electron affinities estimated

Electron affinities may be estimated using a Born-Haber cycle. 

The electron affinity of ClOt has been estimated from a Born—Haber cycle, employing a lattice energy calculation, to be 134 kcal mof (V. I. Medeoeyev, L. V. Gurvich, V. N. Kondrat yev, V. A. Medvedev, and Ye, L Frankevich, "Bond Energies, Ionization Potentials and Electron Affinities," St. Martin s Press, New York, N. Y., 1966), whereas the electron affinity of the P atom has been determined spectroscopically to be 79.5 d 0.1 kcal mol (R. S. Berry and C. W. Reimann, J. Ckem. Pkys., 18, 1540 (1963)). 

The energy drop when an extra electron is taken up by an atom is its electron affinity. This is generally estimated indirectly by applying the Born-Haber cycle to ionic compounds (p. 92). 

The availability of laser photodetachment techniques has permitted more accurate experimental determinations of electron affinities. Even so, tables of electron affinities list some calculated values, in particular for the formation of multiply charged ions. One method of estimation uses the Born-Haber cycle, with a value for the lattice energy derived using an electrostatic model. Compounds for which this is valid are limited (see Section 5.15). 

Although Born-Haber cycles in conjunction with estimates of lattice energy from the Born-Lande or Kapustinskii equations were some of the first sources of electron affinities, a variety of methods are now available to produce more reliable values. The newer methods, however, only afford values for the first electron affinity, as represented in Equation (8.15) ... 

The original values given by Weiss (55) in 1935 were all too high this was almost entirely due to the low value used for the heat of hydration of the proton (SH+). The electron affinity of 02 can also be estimated by a Haber-Born cycle on the (ionic) alkali peroxides (M+-Or) as follows ... 

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