Chlorine ionization energies

S = Heat of sublimation of sodium D = Dissociation energy of chlorine / = Ionization energy of sodium = Electron affinity of chlorine Uq = Lattice energy of sodium chloride AHf = Heat of formation of sodium chloride. 

Were we to simply add the ionization energy of sodium (496 kJ/mol) and the electron affin ity of chlorine (—349 kJ/mol) we would conclude that the overall process is endothermic with AH° = +147 kJ/mol The energy liberated by adding an electron to chlorine is msuf ficient to override the energy required to remove an electron from sodium This analysis however fails to consider the force of attraction between the oppositely charged ions Na" and Cl which exceeds 500 kJ/mol and is more than sufficient to make the overall process exothermic Attractive forces between oppositely charged particles are termed electrostatic, or coulombic, attractions and are what we mean by an ionic bond between two atoms... 

Between sodium and chlorine, there is a slow rise in ionization energy. For magnesium and aluminum the ionization energy is still rather low. Hence electrons are readily lost and positive ions can be expected to be important in the... 

Experimentally we discover that AZ/(Nad) is much larger, 98.0 kcal—a discrepancy of 98 — 37 = 61 kcal. This discrepancy is explained in terms of the large difference in ionization energy of sodium and chlorine atoms ... 

Because the electron has a lower energy when it occupies one of the atom s orbitals, the difference E(C1) — E(Cl-) is positive and the electron affinity of chlorine is positive. Like ionization energies, electron affinities are reported either in electronvolts for a single atom or in joules per mole of atoms. 

On the basis of the ionization energies given, what is most likely to be the compound produced when chlorine reacts with element X ... 

Let s consider the bond formation between sodium and chlorine, a metal and a nonmetal. The electronegativity values of sodium and chlorine are 0.9 and 3.0 respectively. This tells us that sodium has a low ionization energy and a tendency to give electrons while chlorine has a tendency to take electrons. 

A metal, X, reacts with chlorine to form the compound XCI2. The metal s third ionization energy is significantly larger than its first and second ionization energies. 

The ionization energy of chlorine is 299 kcal/mole and its electron affinity is 86 kcal/mole, making separated ions C1+ and Cl unstable relative to atoms by 213 kcal/mole (see Chap. 13). The Coulomb energy —e /R of two ions at the Cl—Cl equilibrium distance 1.988 A is —166 kcal/mole, and the extreme... 

The enthalpy of atomization of copper does not differ at all for the two compounds, and the atomization of chlorine adds only a small difference for the second mole of chlorine. The major energy cost for CuCl2 is the second ionization energy of copper which is compensated by the electron affinity to form the second chloride ion and especially the lattice energy. Since the electron ionized to form Cu2 is a d electron and does not break a noble gas structure, IE2 is not excessive, and both CuCl and CuCl2 are stable compounds. 

Fig. 5.32 Ionization energy-electron affinity curves for fluorine and chlorine. The electronegativities are given by the slopes of these curves. This figure is an enlarged portion of Fig. 2.13...

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