Atomic properties, trend

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... 

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. 

As described in Section 6-, energy must be supplied to break any chemical bond. Bond energies, like bond lengths, vary in ways that can be traced to atomic properties. There are three consistent trends in bond strengths ... 

Electron Configurations, Atomic Properties, and Periodic Trends... 

An element s tendency towards partitioning into solid phases is related to its fundamental atomic properties. These properties follow periodic trends, giving rise to the trends shown in Figure 11.5 for the oceanic residence times of the elements. In the broadest sense, these trends reflect the relative tendency of an element towards electrostatic versus covalent interactions. Chemists have devised various measures of this tendency, such as an element s electronegativity and its ionization potential. The latter is a predictor of electrostatic interactions and is defined as the ratio, z /r, where... 

After going through this exercise in pure spontaneity, let us carry out a harsher analysis of our fundamental data. Abundances in the Solar System reveal trends that directly reflect not the chemical or atomic properties of elements, but rather the characteristics of the nuclei of those elements. The key to understanding the abundance table thus lies in nuclear physics." ... 

A Brief Summary of Atomic Theory, the Basis of the Periodic Table and Some Trends in Atomic Properties... 

Clusters of Ag atoms have metal-like properties at 55 atoms, but they are not metals. The gap between HOMO and LUMO being 0.2 eV is still 10 times larger than kT expected for a bulk metal. The work function is calculated to be 1 eV larger than that of the bulk, and the cohesive energy is only about one-third that expected for bulk. The electrons behave like free electrons. The trend in each of these quantities with size is in the direction from single atom properties toward bulk metal properties. Ousters of Pd have characteristics that differ from bulk metal properties in much the same way as do Ag clusters. One exception is the calculated number of unoccupied d states per atom of small clusters, which is very close to bulk values of 0.6. 

The bond angles in H20, HOF, and 0F2 are 104.5, 97, and 103°, respectively. In terms of the orbitals used and atomic properties, explain this trend. 

The ionization radii calculated for all atoms with this procedure show remarkable periodicity that mirrors many trends observed or inferred empirically for atomic properties such as electronegativity, covalent radii etc. Also indicated is a simple explanation for promotion of atoms into their valence state, before a chemical reaction commences [114]. This generally accepted mechanism, never satisfactorily explained before, can be accounted for simply in terms of environmental pressure. Whenever an atom is crowded because of high pressure or temperature or even concentration on a catalytic surface, the valence electron becomes promoted towards its ionization limit. In this limit the atom enters the valence state as an electron becomes decoupled from... 

Since so much can be predicted or at least rationalized on the basis of the periodicity of a few simple atomic properties, especially Pauling electronegativity, size, and charge (or oxidation number) see Oxidation Number) of the atoms or ions involved, we begin by looking at these trends in some detail (beyond that done in General Chemistry courses) and... 

We have developed a fairly complete picture of polyelectronic atoms that is quite successful in accounting for the periodic table of elements. We will next use the model to account for the observed trends in several important atomic properties ionization energy, electron affinity, and atomic size. 

In this section we have seen that the trends in atomic properties summarized by the periodic table can be a great help in understanding the chemical behavior of the elements. This fact will be emphasized over and over as we proceed in our study of chemistry. 

What atomic property affects periodic trends down a group in the periodic table ... 

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