Structure of the Periodic Table

This is, of course, the principle behind the structure of the periodic table. Elements within a given vertical group resemble one another chemically because chemical properties repeat themselves at regular intervals of 2,8,18, or 32 elements. 

This procedure gives the ground-state electron configuration of an atom. Any other arrangement corresponds to an excited state of the atom. Note that we can use the structure of the periodic table to predict the electron configurations of most elements once we realize which orbitals are being filled in each block of the periodic table (see Fig. 1.44). 

The colors of fireworks depend on the energies of the atomic orbitals of the various atomic ions, but orbital energy levels have consequences that are much more far-reaching. Orbital energies determine the stabilities of atoms and how atoms react. The structure of the periodic table is based on orbital energy levels. In this chapter we explore the details of orbital energies and relate them to the form and structure of the periodic table. This provides the foundation for interpreting chemical behavior patterns. 

The shells play a leading role in the structure of the Periodic Table. This graphic representation is borrowed from the Bohr atomic model. Historically, the shells were assigned letters, nowadays... 

This experiment established the nuclear model of the atom. A key point derived from this is that the electrons circling the nucleus are in fixed stable orbits, just like the planets around the sun. Furthermore, each orbital or shell contains a fixed number of electrons additional electrons are added to the next stable orbital above that which is full. This stable orbital model is a departure from classical electromagnetic theory (which predicts unstable orbitals, in which the electrons spiral into the nucleus and are destroyed), and can only be explained by quantum theory. The fixed numbers for each orbital were determined to be two in the first level, eight in the second level, eight in the third level (but extendible to 18) and so on. Using this simple model, chemists derived the systematic structure of the Periodic Table (see Appendix 5), and began to... 

The goal of this chapter is to help you relate the properties of elements to their position on the periodic table. These properties include ionization energies and electron affinities. You may want to review the basic structure of the periodic table in Chapter 2 and electron configurations in Chapter 7. And Don t forget — Practice, Practice, Practice. 

In this section, you have seen how a theoretical idea, the quantum mechanical model of the atom, explains the experimentally determined structure of the periodic table, and the properties of its elements. Your understanding of the four quantum numbers enabled you to write electron configurations and draw orbital diagrams for atoms of the elements. You also learned how to read the periodic table to deduce the electron configuration of any element. 

The configuration of electrons around the nuclei of atoms is related to the structure of the periodic table. Chemical properties of elements are mainly determined by the arrangement of electrons in the outermost valence shells of atoms. (Other factors also influence chemical... 

Notice the similarities between the two parts of Table 1.1 and the form of the Periodic Table given in Figure 1.3. The quantum rules, the Pauli exclusion principle and the aufbau principle combine to explain the general structure of the Periodic Table. 

R. J. Puddephatt and P. K. Monaghan, The Periodic Table of the Elements, 2nd edn., Oxford University Press, Oxford, 1986. A concise description of the structure of the Periodic Table and a discussion of periodic trends of many physical and chemical properties of the elements. 

Figure 1.1 Principal features of the periodic table. The International Union of Pure and Applied Chemistry (IUPAC) now recommends Arabic group numbers 1-18 in place of the traditional Roman I—VIII (A and B). Group names include alkali metals (1), alkaline earth metals (2), coinage metals (11), chalcogens (16), and halogens (17). The main groups are often called the s,p block, the transition metals the d, block elements, and the lanthanides and actinides the / block elements, reflecting the electronic shell being filled. (See inside front cover for detailed structure of the periodic table.)...

The prediction of the structure of the periodic table from symmetries is one of the great successes of representation theory. It is more than just an application of mathematical techniques to calculations that arise in physics (such as the use of complex analysis to calculate contour integrals). It is an example of the foundational importance of mathematics in physics. 

In the end, dimension is important physically because we can associate a certain complex vector space to each orbital type, and the dimension of the complex vector space tells us how many different states can fit in each orbital of that type. Roughly speaking, this insight, along with the Pauli exclusion principle, determines the number of electrons that fit simultaneously into each shell. These numbers determine the structure of the periodic table. 

Extensive studies of energy spectra and other characteristics of atoms and ions allow one to reveal general regularities in their structure and properties [255-257]. For example, by considering the lowest electronic configurations of neutral atoms, we can explain not only the structure of the Periodical Table of elements, but also the anomalies. The behaviour of the ionization energy of the outer electrons of an atom illustrates a shell structure of electronic configurations. 

Almost all chemical properties can be explained in terms of the properties of atoms, so this material is central to developing an understanding of chemistry. The topics we cover here account for the structure of the periodic table, the great organizing principle of chemistry, and provide a basis for understanding how elements combine to form compounds. The material is also important because it introduces the theory of matter known as quantum mechanics, which is essential for understanding how electrons behave. 

An atom is the smallest particle of an element that still has all the properties of that element. Atoms are made up of three main particles. Protons and neutrons come together in an atom s nucleus, whereas electrons orbit the nucleus. The number of protons in an atom determines what type of element it is. The structure of the periodic table comes from the fact that electron shells are filled in a specific pattern. The rows of the table are called periods and the columns are called groups. There are other ways to divide up the table, as well. 

This exercise will help your understanding of the periodic or repeating, patterns shown by the elements. It will also support your understanding of the structure of the Periodic Table in Groups of elements, and help you begin to predict properties within these Groups. 

Prompted by the structure of the periodic table of the elements, electrons were assumed to occur in concentric shells around the nucleus with a positive charge of Z units, equal to the number of extranuclear electrons. In any period of 8 elements, arranged in order of increasing Z, electrons are postulated to occupy an increasing number of sites (from 1 to 8) at the corners of a cube centred at the nucleus. Any vacancy in the shell of eight enables the relevant atom to share an electron with a neighbouring atom to form a covalent bond and to complete the octet of electrons for that shell. This view has now endured for almost hundred years and still forms the basis for teaching elementary chemistry. The simple planetary model, proposed by Bohr, allows for only one electron per orbit and has little in common with the Lewis model. 

Such enthusiasm is unfortunate in science. It provides little incentive for further analysis once a problem is declared solved. The structure of the periodic table is a problem of this type as a chemical problem it refers to systems, conditioned by their environment, and not to an isolated entity such as a hydrogen atom. The energy spectrum of a hydrogen electron can therefore, by... 

The structure of the periodic table is closely related to energy levels and the arrangement of electrons. Two important patterns result from this relationship. One involves periods, and the other involves groups. 

You have seen that the structure of the periodic table is directly related to energy levels and arrangements of electrons. The patterns that emerge from this relationship enable you to predict the number of valence electrons for any main group element. They also enable you to predict the number of energy levels that an element s electrons occupy. The relationship between electrons and the position of elements in the periodic table leads to other patterns, as well. You will examine several of these patterns in the next section. 

The whole structure of the Periodical Table is connected with the competition between (high n, low /) and (lower n, higher I) shells in a central field U(r) having the property that the product r U smoothly decreases from Z at the nucleus (the... 

Explain the structure of the periodic table and periodic trends in the properties of atoms... 

Describe the structure of the periodic table, and predict chemical and physical properties of an element based on those of others in its group and period (Section 3.1, Problems 1-4). 

Use the group structure of the periodic table to predict the empirical formulas for the binary compounds that hydrogen forms with the elements antimony, bromine, tin, and selenium. 

The subshells (see Fig. 5.12) determine the structure of the periodic table and the formation of chemical bonds. In preparation for a discussion of these connections, it is necessary to describe the energy values for Hartree orbitals. 

FIGURE 5.17 The filling of shells and the structure of the periodic table. Only the "anomalous" electron configurations are shown. 

The Hartree orbitals are the foundation of the quantum explanation of atomic structure. They justify the shell model of the atom, they explain the structure of the periodic table, and they provide the starting point for the quantum explanation of chemical bond formation in the following chapter. 

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