Periodic trends atomic size

Summarize the trend in metallic character as a function of position in the periodic table. Is it the same as the trend in atomic size The trend in ionization energy ... 

There are similar, but smaller, trends in the properties of elements in a column (a family) of the periodic table. Though the elements in a family display similar chemistry, there are important and interesting differences as well. Many of these differences are explainable in terms of atomic size. 

We see that, no matter what type of bonding situation is considered, there is a trend in size moving downward in the periodic table. The alkaline earth atoms become larger in the sequence Be < Mg < Ca < Sr < Ba. These atomic sizes provide a basis for explaining trends in many properties of the alkaline earth elements and their compounds. 

Because most of the volume of an atom is occupied by its electron cloud, the size of an atom is determined by the sizes of its orbitals. Atomic size follows these periodic trends ... 

The computational bond-length variations in Table 4.53 exhibit the expected periodic trends. Most noticeably, third- and second-series elements for groups 4, 6, and 10 exhibit similar bond lengths, i.e., the post-lanthanide contraction with respect to the ordinary increase of atomic size with increasing Z. 

Although periodic trends in enthalpies of formation are often striking, these trends can in general not be used to estimate accurate data for compounds where experimental data are not available. Other schemes are frequently used and these estimates are often based on atomic size and electronegativity-related arguments. As an example, the enthalpy of formation of a ternary oxide from the binary constituent oxides, i.e. the enthalpy of a reaction like... 

Sketch an outline of the periodic table and use it to compare the trends in atomic size, first ionization energy, and electron affinity. 

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. 

The group 4A elements exemplify the increase in metallic character down a group in the periodic table Carbon is a nonmetal silicon and germanium are semimetals and tin and lead are metals. The usual periodic trends in atomic size, ionization energy, and electronegativity are evident in the data of Table 19.4. 

In addition to the information below, the periodic table shows trends in atomic size, ionization energy, electronegativity, valence electrons, and melting points. 

Periodic trends—Going from left to right across a period, atomic size tends to decrease. This occurs because of an increase in nuclear charge, which pulls the electrons in more tightly (thus making the atoms smaller). The noble gases are the smallest elements in each period. 

It has already been emphasized that within a family of non transition elements, metallic character increases with increase in atomic number, atomic weight, and atomic size. There is no better illustration of this trend than Periodic Group Vb the lightest members of the group, nitrogen (Z = 7), and phosphorus (Z — 15), are typical nonmetals, whereas the heaviest member, bismuth (Z = 83) is a typical metal. The remaining members, arsenic (Z = 33) and antimony (Z 51) are intermediate in character and are often appropriately called metalloids. 

Periodic Trends Involving the Sizes and Energy Levels of Atoms... 

Identify periodic trends involving atomic size, ionization energy, and electron affinity. 

Periodic trends for electronegativity (bars) and atomic size (spheres) are inversely related. 

Chemistry is primarily concerned not with the properties of single molecules but with periodic trends, homologous series and the like. It is, therefore, important that any method which we apply to the problem of molecular electronic structure depends linearly on the number of electrons in the system being studied. Meaningful comparisons of atoms and molecules of different sizes are then possible. This property has been termed size-consistency1-2. Independent electron models, such as the widely used Hartree-Fock approximation, provide a size-consistent theory of atomic and molecular structure. 

Figure 13.1 General Periodic Trends in Atomic Size...

There are few periodic generalizations that can be made concerning hypervalent molecules, since the factors contributing to stability, such as oxidation potential, central atom size, type of ligands, and ionic versus covalent bonding type, all interact in a complex manner. However, some general trends are evident. 

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. 

Describe periodic trends in ionic size, electron affinity, and melting and boiling points, and relate them to the atomic structures of the elements. 

No. If all you know is that the atomic number of one element is 20 greater than that of the other, then you will be unable to determine the specific groups and periods that the elements are in. Without this information, you cannot apply the periodic trends in atomic size to determine which element has the larger radius. 

I See the Saunders Interactive General Chemistry CD-ROM, Screen 8.10, Atomic Properties and periodic Trends Size. 

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