Inner transition element oxidation numbers

The rules above gave maximum and minimum oxidation numbers, but those might not be the only oxidation numbers or even the most important oxidation numbers for an element. Elements of the last six groups of the periodic table for example may have several oxidation numbers in their compounds, most of which vary from each other in steps of 2. For example, the major oxidation states of chlorine in its compounds are -1, +1, +3, +5, and +7. The transition metals have oxidation numbers that may vary from each other in steps of 1. The inner transition elements mostly form oxidation states of + 3, but the first part of the actinoid series acts more like transition elements and the elements have... 

Symbol La atomic number 57 atomic weight 138.91 a rare-earth transition metal, precursor to a series of 14 inner-transition elements known as the lanthanide series electron configuration [XejSdiGs oxidation state -i-3 atomic radius 1.879A ionic radius (LaS+) 1.061A electronegativity 1.17 two natural isotopes are La-139 (99.911%) and La-138 (0.089%). 

The two rows beneath the main body of the periodic table are the lanthanides (atomic numbers 58 to 71) and the actinides (atomic numbers 90 to 103). These two series are called inner transition elements because their last electron occupies inner-level 4/orbitals in the sixth period and the 5/orbitals in the seventh period. As with the d-level transition elements, the energies of sublevels in the inner transition elements are so close that electrons can move back and forth between them. This results in variable oxidation numbers, but the most common oxidation number for all of these elements is 3+. 

The lanthanides and actinides, called the inner transition elements, occupy the/region of the periodic table. Their valence electrons are in s and /orbitals. Inner transition elements exhibit multiple oxidation numbers. 

Group electron configuration is ns np. Down the group, the number of oxidation states decreases, and the lower (+2) state becomes more common. Down the group, size increases. Because transition and inner transition elements intervene, IE and EN do not decrease smoothly. 

The simplest homoleptic organometallic derivatives of the lanthanoides in the oxidation state Ln " " are the compounds Ln(CH3)3. The driving force for the inner transition elements to achieve high coordination numbers forcasts a high reactivity for these compounds. Thus, for a long time, only indirect evidence could be found for the existence of such derivatives, and the isolation and characterization of compounds belonging to this class was not possible before the last decade. 

Scandium is the first element in the fourth period of the transition elements, which means that the number of protons in their nuclei increases across the period. As with all the transition elements, electrons in scandium are added to an incomplete inner shell rather than to the outer valence shell as with most other elements. This characteristic of using electrons in an inner shell results in the number of valence electrons being similar for these transition elements although the transition elements may have different oxidation states. This is also why all the transition elements exhibit similar chemical activity. 

Symbol Nd atomic number 60 atomic weight 144.24 a rare earth lanthanide element a hght rare earth metal of cerium group an inner transition metal characterized by partially filled 4/ subshell electron configuration [Xe]4/35di6s2 most common valence state -i-3 other oxidation state +2 standard electrode potential, Nd + -i- 3e -2.323 V atomic radius 1.821 A (for CN 12) ionic radius, Nd + 0.995A atomic volume 20.60 cc/mol ionization potential 6.31 eV seven stable isotopes Nd-142 (27.13%), Nd-143 (12.20%), Nd-144 (23.87%), Nd-145 (8.29%), Nd-146 (17.18%), Nd-148 (5.72%), Nd-150 (5.60%) twenty-three radioisotopes are known in the mass range 127-141, 147, 149, 151-156. 

A number of observers have reported on the adsorption affinity of different metal cations for clays (cf. Farrah et al. 1980) and for hydrous oxides, organic matter, soils, and sediments (cf. Kin-niburgh and Jackson 1982 Loux et al. 1989). There is evidence that the adsorption tendency of divalent transition elements by hydrous oxides often follows the Irving-Williams order (see Chap. 3). This suggests that the absorbed metal cations form inner sphere complexes which occupy the zero plane, and that the sequence of decreasing adsorption tendency is... 

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. 

Outer ns electrons are close in energy to the inner (n - 1)d electrons, which allows transition elements to use several different numbers of electrons in bonding. For this reason, transition elements have multiple oxidation states, in which the lower states display more metallic behavior (ionic bonding and basic oxides). The compounds of ions with a partially filled dsublevel are colored and paramagnetic. (Section 22.1)... 

X-ray spectroscopy rivals visible spectroscopy as a tool for elemental analysis. Because the energies of x-rays are much higher than those of visible radiation, however, x-rays usually cause transitions of inner-shell electrons rather than of valence-shell electrons. There are many advantages of this method in spectrochemical analysis. A quantitative analysis of a mixture of rare-earth oxides may be performed or a crystal structure may be determined. A specimen that contains two elements widely separated in atomic number may be studied, or the thickness of a very thin layer of tin plating may be measured. The most widespread use of x-rays has been in the field of metallurgy, but x-rays may also be used to analyze metals, minerals, liquids, glasses, ceramics, or plastics. 

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