Transition elements electron configurations

Table 1.17 Electronic configuration and crystal field stabilization energies for 3d electrons in transition elements. (Ar) = argon core s 2s 2p 3s 3p. ...

From the chemical point of view, the lanthanoid elements are characterized by a regular variation of their 4f electron configuration throughout the series. Table 2-1. Due to the nature of the orbital group, (n-2) involved in the variation of their electron configuration, these elements are often referred to as the first inner transition series. Inherent to this peculiar electron configuration, the lanthanoid elements show a number of atomic properties that are considered to determine the chemical and structural properties of their compounds, and, particularly, those of their oxides. 

General Principles of Electron Configurations Transition and Inner Transition Elements... 

Polyatomic molecules cover such a wide range of different types that it is not possible here to discuss the MOs and electron configurations of more than a very few. The molecules that we shall discuss are those of the general type AFI2, where A is a first-row element, formaldehyde (FI2CO), benzene and some regular octahedral transition metal complexes. 

Titanium is the first member of the t7-block transition elements. Its electron configuration is [Ar] and successive ionisation potentials are 6.83,... 

The unique nature of the electronic configuration of copper, which contributes to its high electrical and heat conductivity, also provides chemical properties intermediate between transition and 18-sheU elements. Copper can give up the 4s electron to form the copper(I) ion [17493-86-6] or release an additional electron from the >d orbitals to form the copper(Il) ion [15158-11-9]. 

As you can see from Figure 6.9, the electron configurations of several elements (marked ) differ slightly from those predicted. In every case, the difference involves a shift of one or, at the most, two electrons from one sublevel to another of very similar energy. For example, in the first transition series, two elements, chromium and copper, have an extra electron in the 3d as compared with the 4s orbital. 

There are two immediate questions we ask about the transition elements once we know where they are in the periodic table (1) Why do we consider these elements together (2) What is special about their properties These questions are closely related because they both depend upon the electron configurations of the atoms. What, then, is the electron configuration we might expect for these elements ... 

Table 22-1. the electron configurations of the fourth-row transition ELEMENTS... 

Make an electron configuration table like Table 22-1 for the fifth-row transition elements— yttrium (Z = 39) through cadmium (Z = 48). In elements 41 through 45, one of the 5s electrons moves over to a 4d orbital. In element 46, two electrons do this. 

According to this assignment the differentiating electron, that is, the final electron to enter the atom of lutetium, wss seen as an f electron. This suggested that lutetium should be the final element in the first row of the rare earth elements, in which f electrons are progressively filled, and not a transition element as had been believed by the chemists. As a result of more recent spectroscopic experiments the configuration of ytterbium has been altered to (27)... 

For a threefold degenerate MO occupied by three electrons, a configuration of a triradical having a quartet multiplicity is required hy Hund s rule. In organic chemistry, systems of this type occur rarely but with transition element complexes, quartets, quintets, and sextets, they are common. 

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