Ionization energy block metals

The low ionization energies of elements at the lower left of the periodic table account for their metallic character. A block of metal consists of a collection of cations of the element surrounded by a sea of valence electrons that the atoms have lost (Fig. 1.53). Only elements with low ionization energies—the members of the s block, the d block, the f block, and the lower left of the p block—can form metallic solids, because only they can lose electrons easily. 

The usefulness of the main-group elements in materials is related to their properties, which can be predicted from periodic trends. For example, an s-block element has a low ionization energy, which means that its outermost electrons can easily be lost. An s-block element is therefore likely to be a reactive metal with all the characteristics that the name metal implies (Table 1.4, Fig. 1.60). Because ionization energies are... 

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). 

Self-Test 16.1A Predict trends in ionization energies of the d-block metals. 

The s-block metals have low ionization energies, which enables them to easily lose electrons in chemical reactions. 

The chemistry of the transition metals is determined in part by their atomic ionization energies. Metals of the 3d and 4d series show a gradual increase in ionization energy with atomic number (Z), whereas the trend for the 5d series is more pronounced (Figure 20-3). First ionization energies for transition metals in the 3d and 4d series are between 650 and 750 kJ/mol, somewhat higher than the values for Group 2 alkaline earth metals but lower than the typical values for nonmetals in the p block. 

The alkali metals in Group 1(a) have the lowest ionization energies, which is again expected since they always form cations with a +1 valence. There is little variation in I across the d-block and f-block elements, with a slight increase in / as the atomic number increases. 

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,... 

Table 2.1 Valence shell electron configurations, first and second ionization energies E, atomic radii and some ionic radii of the d-block metals...

Gas Phase Photoelectron Spectra of d- and /-Block Organometallic Compounds Table 10. Ionization energies (eV) of lanthanide and actinide cyclopentadienyl metal halides... 

The ionization energies of the 5 -block metals are considerably lower, thus making it easier for them to lose electrons in chemical reactions. 

The block of elements between Group 2 and Group 13 of the Periodic T able are known as the transition eiements or d-biock eiements (Sc to Zn and the elements below them). The eiements of the first transition series are those elements that have partly filled d orbitals in any of their common oxidation states, which are the block of elements headed by Ti to Cu. Here, we will look mainly at the properties of the first transition series Ti, V, Cr, Mn, Fe, Co, Ni and Cu. These elements are typical metals and are often referred to as the transition metals. They have very similar physical properties. The changes in the atomic radii and first ionization energies across the first transition series are small, because each increase in nuclear charge is well shielded by the inner 3d electrons and only a small increased attraction is noticed by the outer electrons in the 4s subshell. See Box 12.7. 

The s- andp-block elements show a larger range of values than do the transition-metal elements. Generally, the ionization energies of the transition metals increase slowly from left to right in a period. The /-block metals (not shown in Figure 7.9) also show only a small variation in the values of Ij. 

For metals exhibiting variable oxidation states, the relative thermodynamic stabilities of two ionic halides that contain a common halide ion but differ in the oxidation state of the metal (e.g. AgF and AgF2) can be assessed using Bom Haber cycles. In such a reaction as 17.19, if the increase in ionization energies (e.g. M — M versus M— M +) is approximately offset by the difference in lattice energies of the compounds, the two metal halides will be of about equal stability. This commonly happens with block metal halides. 

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