Subshells of electrons

Untersatz, m. support, stand, base stay saucer assumption, -schale, /. supporting dish subshell (of electrons), -schali, m. (Phyei s) subsonics. 

This problem clearly did not worry Stoner, who just went ahead and assumed that three quantum numbers could be specified in many-electron atoms. In any case, Stoner s scheme solved certain problems present in Bohr s configurations. For example, Bohr had assigned phosphorus the configuration 2,4,4,41, but this failed to explain the fact that phosphorus shows valencies of three and five. Stoner s configuration for phosphorus was 2,2,2,4,2,2,1, which easily explains the valencies, since it becomes plausible that either the two or the three outermost subshells of electrons form bonds. 

The assumption that only the outermost subshell of electrons contributes to either a or EL. 

Nonmetals follow the general trends of atomic radii, ionization energy, and electron affinity. Radii increase to the left in any row and down any column on the periodic table. Ionization energies and electron affinities increase up any column and towards the right in any row on the periodic table. The noble gases do not have electron affinity values. Ionization energies are not very important for the nonmetals because they normally form anions. Variations appear whenever the nonmetal has a half-filled or filled subshell of electrons. The electronegativity... 

Bohr clearly distinguished chemical properties due to outer electrons from radioactivity due to the interior of the atom, substituting the notion of "shells" and "subshells" of electrons for the earlier idea of "orbits" or circles and relating the filling of these shells to properties of groups within the periodic table. 135 The full import of this paper was not appreciated until after the war, by which time Bohr had changed his mind about some aspects of the theory. 

It has been pointed out above that two electrons in the Is orbital must have their spins opposed, and hence give rise to the singlet state So, with no spin or orbital angular momentum, and hence with no magnetic moment. Similarly it is found that a completed subshell of electrons, such as six electrons occupying the three 2p orbitals, must have S — 0 and L = 0, corresponding to the Russell-Saunders term symbol lS0 such a completed subshell has spherical symmetry and zero magnetic moment. The application of the Pauli exclusion prin-... 

The elements display a periodicity of electronic conf uration. For example, if we examine the detailed electronic configurations of the alkali metals, we find that the outermost shell (specifically, the s subshell) of electrons contains only a single electron in each case. The alkahne earth metals have two outermost electrons. The elements within each other group of the periodic table also have similarities in their outermost electronic configurations. We deduce that the outermost part of the electronic configuration is the main factor that determines the chemical properties of the elements because the periodic table was constructed from data about the properties of the elements. 

Note that although the general trend is for ionization energies to increase toward the right, some small exceptions exist (see Figure 13.3). Many of these stem from the extra stability of a half-filled subshell of electrons. 

As a transition metal with a partially filled d-subshell of electrons, the UV-Vis spectroscopy of iron is a sensitive measure of both the first coordination shell environment (ligand field), and oxidation and spin state of the metal. Ligand field bands are an excellent experimental handle for spectroelectrochemistry, and in the case of heme proteins the Soret band provides an additional probe for... 

Zinc is a trace element (with an abundance of 0.0076%) in Earth s crust. Like the other elements in its family, zinc is found predominantly as a sulfide compound (ZnS). Pure zinc is a silver-white solid at room temperature. Like other metals, zinc conducts electricity and can be formed into wires or sheets. Some properties of zinc are quite different from those of the other transition metals— namely, its relatively low melting point, boiling point, and density. These different properties are attributed to zinc s full outermost subshell of electrons, which also causes it to be relatively unre-active. 

These elements show a kind of mini-periodicity [2] of characteristic extreme oxidation states, as seen in Table 3.1. A few of these known oxidation states, which represent exactly empty, half-full or full f subshells of electrons, are nevertheless not stable in water, as will be seen in the descriptions below. Table 3.2... 

There is no single best form of the periodic table since the choice depends on the purpose for which the table is used. Some forms emphasize chemical relations and valence, whereas others stress the electronic configuration of the elements or the dependence of the periods on the shells and subshells of the atomic structure. The most convenient form for our purpose is the so-called long form with separate panels for the lanthanide and actinide elements (see inside front cover). There has been a lively debate during the past decade as to the best numbering system to be used for the individual... 

Let us now derive the Slater-Kirkwood38 formula in terms of our present quantities. A single subshell of equivalent electrons is assumed. Equation 29 may be rearranged to... 

Our earlier discussion of off-diagonal s, however, indicated that 2Q would substantially exceed in many-electron systems. Consequently, if Eq. 34 is used with N an empirical factor,31 we may expect the N values to exceed substantially the actual number of electrons of the outer subshell. 

Slater-Kirkwood theory N = no. of electrons of outer subshell empirical evaluated from EL and correlate with actual number of electrons of both outer subshell and of whole system. 

Boron (Z = 5) has five electrons. Two enter the ls-orbital and complete the n = 1 shell. Two enter the 2s-orbital. The fifth electron occupies an orbital of the next available subshell, which Fig. 1.41 shows is a 2p-orbital. This arrangement of electrons is reported as the configuration 1 s22s22p1 or He 2s22/ 1 (5), showing that boron has three valence electrons. 

Write the subshell notation (3d, for instance) and the number of electrons that can have the following quantum numbers if all the orbitals of that subshell are filled (a) n = 3,... 

FIGURE 2.2 When a main-group metal atom forms a cation, it loses its valence s-and p-electrons and acquires the electron configuration of the preceding noble-gas atom. The heavier atoms in Croups 1 S/lll and 14/IV retain their complete subshells of d-electrons. 

Depending on the permitted values of the magnetic quantum number m, each subshell is further broken down into units called orbitals. The number of orbitals per subshell depends on the type of subshell but not on the value of n. Each orbital can hold a maximum of two electrons hence, the maximum number of electrons that can occupy a given subshell is determined by the number of orbitals available. These relationships are presented in Table 17-5. The maximum number of electrons in any given energy level is thus determined by the subshells it contains. The first shell can contain 2 electrons the second, 8 electrons the third, 18 electrons the fourth, 32 electrons and so on. 

Type of Subshell Allowed Values of m Number of Orbitals Maximum Number of Electrons... 

The shell number is represented by 1, 2, 3, and so forth, and the letters designate the subshells. The superscript numbers tell how many electrons occupy each subshell. Thus, in this example, there are two electrons in the Is subshell, two electrons in the 2s subshell, six electrons in the 2p subshell, and only one electron in the 3s subshell. (The 3s subshell can hold a maximum of two electrons, but in this atom this subshell is not filled.) The total number of electrons in the atom can easily be determined by adding the numbers in all the subshells, that is, by adding all the superscripts. For sodium, this sum is 11, equal to the atomic number of sodium. 

In atoms with partially filled p, d, or / subshells, the electrons stay unpaired as much as possible. This effect is called Hund s rule of maximum multiplicity. Thus the configuration of the nitrogen and oxygen atoms are as follows ... 

---