Trends in Ionization Energies

The ionization energy (IE) is the energy (in kJ) required for the complete removal of 1 mol of electrons from 1 mol of gaseous atoms or ions. Pulling an electron away from a nucleus requires energy to overcome the attraction. Because energy flows into the system, the ionization energy is always positive (like A// of an endothermic reaction). 

In Chapter 7, you saw that the ionization energy of the H atom is the energy difference between n = 1 and = o°, the point at which the electron is completely removed. Many-electron atoms can lose more than one electron. The first ionization energy (IE,) removes an outermost electron (highest energy sublevel) from the gaseous atom  

The second ionization energy (IE2) removes a second electron. This electron is pulled away from a positively charged ion, so IE2 is always larger than IE lon (g)-------------------- ion (g) + e AE = IE2 (always IE ) 

The first ionization energy is a key factor in an element s chemical reactivity because, as you ll see, atoms with a lowIEj tend to form cations during reactions, whereas those with a high lEj (except the noble gases) often form anions. 

Across a period. As we move left to right across a period, the orbital s n value stays the same, so Zeir increases and atomic size decreases. As a result, the attraction between nucleus and outer electrons increases, which makes an electron harder to remove. Ionization energy generally increases across a period it is easier to remove an outer electron from an alkali metal than from a noble gas. 

The second ionization energy (IE2) removes a second electron. This electron is pulled away from a positively charged ion, so TE2 is always larger than IE  

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

Figure 8-16 shows how the first ionization energies of gaseous atoms vary with atomic number. Notice the trends in ionization energy. Ionization energy increases regularly from left to right across each row (Row 3 ... 

A limited number of elements form ionic compounds. As we describe in the next two chapters, most substances contain neutral molecules rather than charged ions. The trends in ionization energies and electron affinities indicate which elements tend to form ions. Ionic compounds form when the stabilization gained through ionic attraction... 

Periodic trends in ionization energy are linked to trends involving the reactivity of metals. In general, the chemical reactivity of metals increases down a group and decreases across a period. These trends, as well as a further trend from metallic to non-metallic properties across a period, and increasing metallic properties down a group, are shown in Table 3.1. 

Trends in ionization energy. The attraction an atomic nucleus has for the outermost electrons in an atom indicated by height. Note that atoms at the upper right tend to have the greatest ionization energy and those at the lower left the least. 

Trends in ionization energies have been illustrated previously but other examples are of particular interest. The halides of Ge, Sn and Pb can be singled out because they have been extensively characterized for both the (IV) and (II) oxidation states. As in the case of C and Si, the tetrafluoro derivatives display very high ionization energies, and the observed trends in Ge demonstrate the decrease in IE in going from F to I, and the decrease in going from the (IV) to the (II) oxidation state, i.e. 

Trends in ionization energy and electron affinity within a period reflect the stability of valence electron configurations. A stable system requires more energy to change and releases less when changed. Note the peaks in stability for groups 2, 13, and 16. 

Figure 13.4 Relative Periodic Trends in Ionization Energy...

Does the information on alkali metals in Table 12.9 of the text confirm the general periodic trends in ionization energy and atomic radius Explain. 

What role does electron-electron repulsion play in the trend in ionization energies from lithium to neon ... 

Describe periodic trends in ionization energy, and relate them to the atomic structures of the elements. 

Explain the trend in ionization energy within a group on the periodic table. 

Periodic trends in ionization energies suggested the shell model of the atom in which electrons occupy concentric shells located at increasing distances from the nuclei. 

Describe the trends in ionization energy across the periodic table (Section 3.3, Problems 9 and 10). 

The Hartree orbitals and the shell model explain periodic trends in ionization energy, electron affinity, and the radii of atoms and ions. Small changes in these properties within a period are further explained by detailed changes in Z ff within that period. 

Here is one reason why trends in ionization energies are important. 

Trends in orbital energy and size reflect changes in the principal quantum number and effective nuclear charge. They are seen experimentally in trends in ionization energy (IE) and apparent radius of atoms. 

The oxidation states +2 and +4 are found for some elements, following the trend in ionization energies across the series, which show patterns analogous to those found in configurations of p and d electrons (see Topics A5 and HI). The third ionization energy rises from La to Eu (see Fig. 1) and... 

The trends in ionization energy caused by changing the metal within a particular subgroup are summarized graphically in Fig. 5c. For the 18e compounds the most... 

Define ionization energy. What are the general trends in ionization energy on the periodic table ... 

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