Gallium ionization energy

Arrange the following atoms in order of increasing first ionization energy boron, thallium, gallium. 

Self-Test 1.14B Account for the fact that the two Group 13 elements aluminum and gallium have approximately the same ionization energies. 

As the group is descended, atomic radii increase and ionization energies are all lower than for boron. There is an increase in polar interactions and the formation of distinct M ions. This increase in metaUic character is clearly Ulustrated by the increasing basic character of the hydroxides boron hydroxide is acidic, aluminium and gallium hydroxides are amphoteric, indium hydroxide is basic, and thaUium forms only the oxide. As the elements of group 13 have a vacant p-orbital they display many electron-acceptor properties. For example, many boron compounds form adducts with donors such as... 

Write equations that show the process for (a) the first two ionization energies of gallium and (b) the fourth ionization energy of rhodium. 

Using Slater s rules, calculate the effective nuclear charge acting on the 3f> valence electron of aluminum. Do a similar calculation for the valence /> electrons of gallium, indium, and thallium, respectively. Comment on the results relative to the first ionization energies of these elements. 

Unexpectedly high ionization energies for gallium, indium and thallium make conversion of the metals into ions more difficult. They are a major contribution to the greater resistance to oxidation revealed in Table 9.3. 

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