Cesium ionization energy

What trend is observed in the first ionization energy as you move from lithium down the column I metals On this basis, can you suggest a reason why potassium or cesium might be used in preference to sodium or lithium in photoelectric cells ... 

The first ionization energy is highest for elements close to helium and is lowest for elements close to cesium. Second ionization energies are higher than first ionization energies (of the same element) and very much higher if the electron is to be removed from a closed shell. Metals are found toward the lower left of the periodic table because these elements have low ionization energies and can readily lose their electrons. 

On the basis of your knowledge of periodicity, place each of the following sets of elements in order of decreasing ionization energy. Explain your choices, (a) Selenium, oxygen, tellurium (b) gold, tantalum, osmium (c) lead, barium, cesium. 

Although the increased electron affinity associated with the heavier elements usually manifests itself only indirectly (via electronegativity, etc.), it is directly responsible for the fact that cesium auride, Cs Au, is an ionic salt rather than an alloy. Both the increased ionization energy and increased electron affinity in these elements result from relativistic effects. 

Figure 1.39 shows that first ionization energies generally decrease down a group. The decrease means that it takes less energy to remove an electron from a cesium atom, for instance, than from a sodium atom. 

An s-block element has a low ionization energy, which means its outermost electrons can be lost easily. A Group 1 element is likely to form +1 ions, such as Li+, Na+, and K+. Group 2 elements similarly form +2 ions, such as Mg2+, Ca2+, and Ba2+. An s-block element is likely to be a reactive metal with all the features that the name metal implies (Fig. 1.48, Table 1.4). Because ionization energies are lowest at the bottom of each group, and the elements there lose their valence electrons most easily, the heavy elements cesium and barium react most vigorously of all s-block elements. They have to be kept stored out of contact with air and water. The alkali metals have few direct uses as materials but are enormously important as compounds. 

The reactivity of an alkali metal increases as its ionization energy decreases, giving a reactivity order Cs > Rb > K > Na > Li. Cesium is the most reactive, combining almost explosively with the halogens. 

Cesium has the smallest ionization energy of all elements (376 kj/mol), and chlorine has the most negative electron affinity (—349 kj/mol). Will a cesium atom donate an electron to a chlorine atom to form isolated Cs+ and Cl- ions ... 

For reactions of this type, the relative reducing powers of the alkali metals can be predicted from the first ionization energies listed in Table 12.9. Since it is much easier to remove an electron from a cesium atom than from a lithium atom, cesium should be the better reducing agent. The expected trend in reducing ability is... 

The first ionzation energies of the main group and transition metals are listed in Table 14.1. The first two series do not differ significantly from each other—sometimes an element of one series is higher, sometimes the other. Beginnirtg with cesium the third series has a noticeably lower ionization energy as we might expect on the basis of... 

Ionization energies (a.u.) for valence states of cesium calculated in second-order perturbation theory. The quantity is the HF energy and is the correction from second-order perturbation theory. 

The altitude of the landscape of ionization energies ranges in height from about 4 eV (at cesium) to 25 eV (at... 

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