Atomic radii within periodic table

Within a given group of the Periodic Table, the radius increases with increasing atomic number. This fact is... 

Within a given group of the periodic table, the first ionization energy decreases with increasing atomic number. This is related to the increase in atomic radius and the decreasing attraction of the nucleus for the increasingly distant outermost electron. It should be mentioned that this trend is not uniformly noted for the transition metals. 

One property of a transition metal ion that is particularly sensitive to crystal field interactions is the ionic radius and its influence on interatomic distances in a crystal structure. Within a row of elements in the periodic table in which cations possess completely filled or efficiently screened inner orbitals, there should be a decrease of interatomic distances with increasing atomic number for cations possessing the same valence. The ionic radii of trivalent cations of the lanthanide series for example, plotted in fig. 6.1, show a relatively smooth contraction from lanthanum to lutecium. Such a trend is determined by the... 

Figure 1 shows atomic radius as a function of atomic number for the first three periods of the periodic table. Within a period the atomic radius decreases as the atomic number increases, but the atomic radius increases as the period increases. 

Figure 8.9 shows the radii of ions derived from the familiar elements, arranged according to elements positions in the periodic table. We can see parallel trends between atomic radii and ionic radii. For example, from top to bottom both the atomic radius and the ionic radius increase within a group. For ions derived from elements in different groups, a size comparison is meaningful only if the ions are isoelectronic. If we examine isoelectronic ions, we find that cations are smaller than anions. For example, Na is smaller than F . Both ions have the same number of electrons, but Na... 

As the magnitude of the positive charge of the nucleus increases, its "pull" on all of the electrons increases, and the electrons are drawn closer to the nucleus. This results in a contraction of the atomic radius and therefore a decrease in atomic size. This effect is apparent as we go across the periodic table within a period. Atomic size decreases from left to right in the periodic table (see Figure 3.7). See how many exceptions you can find in Figure 3.7. 

Elements in the same group of the periodic table possess the same number of electrons in their outer shells and are therefore said to have the same valence electronic configuration, and consequently similar chemical and physical properties. As electrons are filled into the inner shells of an atom, the outer shell takes on a specific valence configuration that is determined by the rules that govern how many electrons can occupy a particular shell, as described above in the section on quantum mechanics. It is this very regularity in the number of outer-shell electrons that explains the periodic behavior shown by the elements as the atomic number increases. Similarly, properties such as atomic size are determined by the number of shells an atom contains. For example, the radius of the atoms of the elements within a particular group in the periodic table increases from the top of the group to the bottom. 

Besides its position in the periodic table, other factors that affect the atomic radius of a transition metal in a coordination complex are (i) the oxidation state, (ii) the spin state, and (iii) the coordination number. An increase in the oxidation state of the metal atom is expected to result in shorter metal-ligand bond distances. However, this fact can only be observed when comparing complexes with the same ligands, since statistically the differences in atomic radii for a metal with different oxidation states, within a large set of complexes, are not significant. Much clearer is the sizable difference in atomic size that a certain metal in a given oxidation state presents for two alternative spin... 

Use trends within the periodic table and indicate which member of each of the following pairs has the larger atomic radius ... 

Figure 7.6 shows the atomic radii of the main group elements according to their positions in the periodic table. There are two distinct trends. The atomic radius decreases as we move from left to right across a period and increases from top to bottom as we move down within a group. 

The relative size of sodium and potassium ions is an example of a periodic property one that is predictable based on an element s position within the periodic table. In this chapter, we examine several periodic properties of elements, including atomic radius, ionization energy, and electron affinity. We will see that these properties, as well as the overall arrangement of the periodic table, are explained by quantum-mechanical theory, which we examined in Chapter 7. The arrangement of elements in the periodic table— originally based on similarities in the properties of the elements— reflects how electrons fill quantum-mechanical orbitals. 

Periodic properties are predictable based on an element s position within the periodic table. Periodic properties include atomic radius, ionization energy, electron affinity, density, and metaUic character. 

Variation of atomic radii within a period of the periodic table. Equation (9.5) suggests that the radius of an atom is approximately proportional to For the main group elements, as we move from left to right across a period, is a constant and, as shown in Figure 9-8(a), Zeff increases rather significantly. Thus, the decrease in radius across the period is attributed to... 

Variation of atomic radii within a group of the periodic table. We have already established that electrons in the outermost shell of an atom are significantly screened by those in inner shells. Thus, for atoms closer to the bottom of the group, the outer electrons occupy orbitals that extend over much larger distances, and we expect the radius of an atom to increase from top to bottom within a group. 

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