Aluminum ionization energies

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... 

Consider the three elements, sodium, magnesium, and aluminum. For each of these elements we know several ionization energies, corresponding to processes such as the following ... 

If we continue to remove electrons from aluminum, we discover a very large increase in ionization energy when the fourth electron is removed. Again this is because the fourth electron must be withdrawn from a 2p orbital, an orbital much lower on the energy level diagram. We conclude that three electrons, the two 35 and the one 3p, are more easily removed than the others. Since aluminum has three easily removed electrons, aluminum is said to have three valence electrons. 

Write out the electron configuration of sodium, magnesium, and aluminum and find the ionization energies for all their valence electrons (Table 20-IV, p. 374). Account for the trend in the heats of vaporization and boiling points (Table 20-1) of these elements. Compare your discussion with that given in Section 17-1.3. 

We have already mentioned that the stability of the metallic crystal and the ionization energies of the atom tend to increase in the series sodium, magnesium, and aluminum. In spite of this, aluminum is still an excellent reducing agent because the hydration energy of the Al+1 ion is very large (Table 20-III). 

We can tell from the ionization energy of aluminum that this atom holds its second and third valence electrons rather firmly. With this fact in mind, we can see why aluminum hydroxide, Al(OH)3, would not be as strongly basic as are the hydroxides, NaOH and Mg(OH>2. Aluminum hydroxide has extremely low solubility in neutral aqueous solutions but does react with strong acids according to the reaction... 

Alpha carbon atoms, 348 Alpha decay, 417, 443 Alpha particle, 417 scattering, 245 Aluminum boiling point, 365 compounds, 102 heat of vaporization, 365 hydration energy, 368 hydroxide, 371 ionization energies, 269, 374 metallic solid, 365 occurrence, 373 properties, 101 preparation, 238. 373 reducing agent, 367 Alums, 403 Americium... 

Elements on the left of the p block, especially the heavier elements, have ionization energies that are low enough for these elements to have some of the metallic properties of the members of the s block. However, the ionization energies of the p-block metals are quite high, and they are less reactive than those in the s block. The elements aluminum, tin, and lead, which are important construction materials, all lie in this region of the periodic table (Fig. 1.61). 

Metallic elements with low ionization energies commonly form basic ionic oxides. Elements with intermediate ionization energies, such as beryllium, boron, aluminum, and the metalloids, form amphoteric oxides. These oxides do not react with or dissolve in water, but they do dissolve in both acidic and basic solutions. 

Ionization energies deviate somewhat from smooth periodic behavior. These deviations can be attributed to screening effects and electron-electron repulsion. Aluminum, for example, has a smaller ionization energy than either of its neighbors in Row 3 ... 

For implanted acceptor activation there have been several reviews during the last few years since Troffer et al. s often-cited paper on boron and aluminum from 1997 [88]. Aluminum is now the most-favored choice of acceptor ion despite the larger mass, which results in substantially more damage compared with implanted boron. Mainly it is the high ionization energy for boron that results in this choice, as well as its low solubility. In addition, boron has other drawbacks, such as an ability to form deep centers like the D-center [117] rather than shallow acceptor states and, as shown in Section 4.3.2, boron ions also diffuse easily at the annealing temperatures needed for activation. The diffusion properties may be used in a beneficial way, although it is normally more convenient if the implanted ion distribution is determined by the implant conditions alone. 

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

Metallic elements with low ionization energies commonly form ionic oxides. As remarked in Section 10.1, the oxide ion is a strong base, so the oxides of most of these metals form basic solutions in water. Magnesium is an exception because its oxide, MgO, is insoluble in water. However, even this oxide reacts with acids, so it is regarded as basic. Elements with intermediate ionization energies, such as beryllium, boron, aluminum, and the metalloids, form amphoteric oxides. These oxides do not react with water, but they do dissolve in both acidic and basic solutions. 

To introduce some of the characteristics of ionization energy, we will consider the energy required to remove several electrons in succession from aluminum atoms in the gaseous state. The ionization energies are... 

Several important points can be illustrated from these results. In a stepwise ionization process, it is always the highest-energy electron (the one bound least tightly) that is removed first. The energy required to remove the highest-energy electron of an atom is called the first ionization energy (Ix). The first electron removed from the aluminum atom comes from the 3p orbital (A1 has the... 

Fig. 4.9 Energies of free cations and of ionic compounds as a function of the oxidation state of the cation. Top Lines represent the ionization energy necessary to form the +1. +2, +3, and + 4 cations of sodium, magnesium, and aluminum. Note that although the ionization energy increases most sharply when a noble gas configuration is broken, isolated cations are always less stable in Itiifher oxidation states. Bottom Lines represent the sum of ionization energy and ionic bonding energy for hypothetical molecules MX, MXj, MXj, and MX in which the interatomic distance, r, has been arbitrarily set at 200 pm. Note that the most stable compounds (identified by arrows) arc NaX, MgXj, and AlXj. (All of the.se molecules will be stabilized additionally to a small extent by the electron affinity of X.)...

In general, ionization energy increases from left to right across a given period. Aluminum, however, has a lower ionization energy than magnesium. Explain. 

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