Subshells outermost

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. 

Again it is a useful approximation to consider just the set of equivalent orbitals of the outermost subshell. Then... 

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

Ans. The maximum number of electrons in any outermost shell (except the first shell) is 8. The fifth shell starts before the d subshell of the fourth shell starts. 

The configuration for Pb2 + is the same except for the loss of the outermost two electrons. There are four electrons in the sixth shell the two in the last subshell of that shell are lost first ... 

Ans. A state of great stability is a state in which the outermost s and p subshells are filled and no other subshell of the outermost shell has any electrons. 

The difference is the extra ten 3d electrons, plus the extra ten protons in the nucleus that go along with them. Adding the protons and adding the electrons in an inner subshell makes the outermost electron more tightly bound to the nucleus. 

For brevity, many chemists record the electron configuration of an atom by giving only its outermost subshell, like As for potassium or 4/ for calcium. These electrons are most distant from the positive nucleus and, therefore, are most easily transferred between atoms in chemical reactions. These are the valence electrons. 

Because of the contraction and stabilization of the 6s orbital, the outermost, or valence, shell of Au is formed by both the 5d and 6s orbitals. Indeed, electronically, Au is halogen-like, with one electron missing from the pseudo noble gas (closed subshell) configuration. Hence, similar to the existence of halogen X2 molecule, gold also forms the covalent Au2 molecule. In addition, gold also forms ionic compounds such as RbAu and CsAu, in which the Au- anion has the pseudo noble gas electronic configuration. 

The trend is that ionization potential increases with increasing Z, except that the nitrogen (with a half-filled subshell) is especially stable and boron (with only one electron beyond a full subshell) parts with its outermost electron inordinately easily. 

Other complications are associated with the partitioning of the core and valence space, which is a fundamental assumption of effective potential approximations. For instance, for the transition elements, in addition to the outermost s and d subshells, the next inner s and p subshells must also be included in the valence space in order to accurately compute certain properties (54). A related problem occurs in the alkali and alkaline earth elements, involving the outer s and next inner s and p subshells. In this case, however, the difficulties are related to core-valence correlation. Muller et al. (55) have developed semiempirical core polarization treatments for dealing with intershell correlation. Similar techniques have been used in pseudopotential calculations (56). These approaches assume that intershell correlation can be represented by a simple polarization of one shell (core) relative to the electrons in another (valence) and, therefore, the correlation energy adjustment will be... 

Valence electrons play a huge role in bonding, as will be shown later. Valence electrons are the electrons that are in the outermost principal energy level (not to be confused with the outermost subshell). These electrons are important because they are the electrons that are lost, gained, or shared when forming chemical bonds. The valence electrons of an atom are the electrons that interact with the valence electrons of another atom to form these bonds. 

Because the last 3 electrons are added to an inner shell (following the + rule) instead of the outermost shell, the 3d subshell of a vanadium atom must be higher in energy than the 4 subshell. 

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. 

The four transition metal series arise because, for each of these elements, an electron has been added to the next-to-outermost shell. Addition of 10 electrons to the 3t subshell after the completion of the 4s subshell causes 10 elements to occur after calcium to be the first elements in their periodic groups. The second, third, and fourth transition series occnr becanse the 4d, 5d, and 6d snbshells add electrons after the start of the fifth, sixth, and seventh shells. 

A more compact notation can sometimes be used to reduce the effort of writing long electronic configurations while retaining almost as much information. We are most interested in the outermost shell and the inner subshells having nearly the same energies. We can therefore write the detailed electronic... 

No matter which rule or memory device we use to write configurations, some transition metals and inner transition metals have configurations different from our expected configurations. Some of these occur because of the added stability associated with half-filled or fully filled subshells. For example, chromium and copper have actual configurations with two such outermost subshells instead of only the fully filled As subshell and 3d subshell neither half nor fully filled, as expected ... 

A. Deduce the outermost electronic configuration of Lr without bothering to assign the inner 86 electrons to subshells. 

How many unpaired electrons are in an atom in the ground state, assuming that all other subshells are either completely full or empty, if its outermost p subshell contains (a) three electrons, (b) five electrons, (c) four electrons ... 

The detailed electronic structures of monatomic ions may be deduced starting from the structures of the corresponding neutral atoms (presented in Chapter 4). Monatomic anions have simply added sufficient electrons to the outermost p subshell to complete that subshell. The + rule can be used to deduce the structure of the ion as well as that of the neutral atom. For example, the electronic configuration of the nitride ion (the anion of nitrogen) is deduced, starting with the configuration of nitrogen ... 

An atom with a total of 8 electrons in its outermost shell (5 and p subshells) is stable. 

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