Lanthanum electronic structure

The electronic structure and chemical bonding in the 15-crown-5 complex of lanthanum trichloride having a coordination number of 8 has been studied. The molecular structure of LaCl3(15-crown-5) and the charge distribution of the complex, ligand and metal chloride are shown in Figs 5.23 and 5.24, respectively. 

The next fourteen elements following lanthanum are called the rare-earth metals. They correspond to the introduction of fourteen additional electrons into the N shell, bringing its total number of electrons up to 32. The remaining elements are similar to those shown directly above them in the periodic table, and their electronic structures are similarly represented. 

In caesium (Z = 55) one electron occupies the 6s orbital of the P shell, and in barium (Z = 56) there are two electrons in this orbital. Thereafter the development of the P shell is interrupted, and lanthanum (Z = 57) initiates the third transition series with one electron in the 5 d orbital of the 0 shell. The development of this series, however, proceeds no further at this stage, and in the elements from cerium (Z = 58) to lutecium (Z = 71) electrons are entering the hitherto vacant 4/orbitals of the N shell. These elements constitute the rare earths or elements of the lanthanide series, and the fact that the differentiating electrons are so deep in the electronic structure is responsible for the close similarity of their chemical properties. 

A.V. Zyrin, T.N. Bondarenko, I.V. Urubkov, V.N. Uvarov, Conductivity and electronic structure of lanthanum nickelites , Mixed Ionic Electronic Conducting Perovskites for Advanced Energy Systems, NATO Science Series, 281-287 (2004). 

Electronic Structures. Almost all the physical properties and chemical behavior of the rare earth elements find a logical explanation in terms of their electronic structures. Scandium, yttrium, lanthanum, and actinium are the first members, respectively, of the first, second, third, and fourth transition sequences of elements. In other words, each such element marks the beginning of an inner building where a stable group of 8 electrons is expanding to a completed (or more nearly complete) group of IS. This situation is illustrated for the first transition sequence. 

The elements after Xe have this electronic configuration, plus electrons in the orbits of 4f, 5d, 6s, and so on. There are three elements. Cesium (Cs), barium (Ba), and lanthanum (La), between Xe and the RE elements. Cs has one 6s electron and Ba has two 6s electrons, while La has two 6s and one 5d electrons. When it comes to RE elements, the electrons start to fill the inner vacant 4f orbits. For instance, the first RE element Ce has only one electron in the f orbit, so that its configuration is [Xe]6s 4f 5d, while neodymium (Nd) has four electrons in the f orbit, i.e., its electron structure is [Xe]6s 4f. ... 

EDXD spectrum, 307/ electronic structure, 306 equation of state, 308/ phase transition, 306 lanthanum... 

This chapter deals extensively with the experimental data on the superconductivity of the rare earth metals at high pressure. The results are discussed from a phenomenological point of view emphasizing systematics. This seems appropriate at the present stage of understanding. The analysis results in rather clear-cut conclusions for the electronic structure of cerium and lanthanum. It is hoped that they will serve as a useful guide-line for future experimental and theoretical work. We would like to summarize the following results and problems. 

The removal of 4f electrons is indeed essential in most oxidation states of these elements, which have the tendency of attaining the stable electronic configuration of La or Xe. In the middle of the series, gadolinium is considered rather stable because of the half--filled 4f subshells. It represents, as La and Lu, a sort of reference element for some regular changes in the chemical behaviour, such as an abnormal valency state. As a matter of fact, all three have one 5d electron besides zero, seven and fourteen 4f electrons (which make empty, half-fulled and fully filled the 4f shells, respectively). Therefore, Ln(III) ions correspond to a stable electronic structure 5s p. Lanthanum and lutetium, together with yttrium, could be formally assumed as d elements (see Tab. 2). 

THE RARE EARTH elements are those from atomic numbers 57 (lanthanum) to 71 (lutetium) inclusive and elements 21 (scandium) and 39 (yttrium). They represent the largest group of chemically similar elements, but their physical properties differ markedly due to subtle features of electronic structure. Because of the similarity between... 

---