Groups ionization energies trends

The radius trend and the ionization energy trend are exact opposites. Does this make sense Define electron affinity. Electron affinity values are both exothermic (negative) and endothermic (positive). Howevei ionization energy values are always endothermic (positive). Explain. Arrange the following groups of atoms in order of increasing size. 

The atomic properties of Ge, Sn and Pb are compared with those of C and Si in Table 10,1, Trends noted in previous groups are again apparent. The pairwise similarity in the ionization energies of Si and Ge (which can be related to the filling of the Sd shell) and of Sn and Pb... 

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... 

All the elements in a main group have in common a characteristic valence electron configuration. The electron configuration controls the valence of the element (the number of bonds that it can form) and affects its chemical and physical properties. Five atomic properties are principally responsible for the characteristic properties of each element atomic radius, ionization energy, electron affinity, electronegativity, and polarizability. All five properties are related to trends in the effective nuclear charge experienced by the valence electrons and their distance from the nucleus. 

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. 

Ionization energy generally decreases down a group. Notice that this trend is the inverse of the trend for atomic radius. The two trends are, in fact, linked. As atomic radius increases, the distance of valence electrons from the nucleus also increases. There is a decrease, therefore, in the force of attraction exerted by the nucleus on the valence electrons. Thus, less energy is needed to remove one such electron. 

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. 

The trends in first ionization energies, first electron attachment energies, atomic sizes and electronegativity coefficients of the elements across the groups and down the periods of the periodic classification. 

What general trends are noticeable down the groups of the Periodic Table in the values of (a) the first ionization energies, (b) the first electron attachment energies and (c) the covalent radii of the elements ... 

The mercury atom is smaller than expected from the zinc-cadmium trend and is more difficult to ionize than the lighter atoms. In consequence the metal-metal bonding in mercury is relatively poor, resulting in the element being a liquid in its standard state. This almost Group 18 behaviour of mercury may be compared to that of a real Group 18 element, xenon, which has first and second ionization energies of 1170 and 2050 kJ mol. ... 

Thallium and lead have higher values of their first ionization energies than expected from the trends down their respective groups, because their p-orbitals are more compact. The relativistic effect upon the 6p-orbitals of the elements from Tl to Rn is to reinforce a stabilization of one orbital with respect to the other two. Instead of the expected trend, the first ionization energies ofTl, Pb and Bi ( + 589, +715 and +703 kJ mol- ) do not show a general increase like those of In, Sn and Sb (+558, +709 and + 834 kJ mol ) the value for Bi is lower than that of Pb. 

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