Series, actinide inner transition

The f-block elements comprise two series of inner transition elements which appear, firstly after lanthanum and secondly after actinium, in the Periodic Table. The elements from cerium to lutetium are known as the lanthanides and, because of its chemical similarity to these elements, lanthanum is usually included with them. Scandium and yttrium also show strong chemical similarities to the lanthanides, so that the chemistry of these elements is also often considered in conjunction with that of the lanthanide series. The second series of f-block elements, from thorium to lawrencium, is known as the actinide series and again it is usual to consider actinium together with this series. 

The second series of inner transition elements, the actinides, have atomic numbers ranging from 90 (thorium, Th) to 103 (lawrencium, Lr). All of the actinides are radioactive, and none beyond uranium (92) occur in nature. Like the transition elements, the chemistry of the lanthanides and actinides is unpredictable because of their complex atomic structures. What could be happening at the subatomic level to explain the properties of the inner transition elements In Chapter 7, you ll study an expanded theory of the atom to answer this question. 

Figure 9.2 gives electronegativity values for the lanthanides and actinides. Notice that the values for both series of inner transition elements do not vary a great deal. Explain why you might have predicted this on the basis of the electron configurations of these elements. (Chapter 7)... 

Evidence other than that of ion-exchange favours the view of the new elements as an inner transition series. The magnetic properties of their ions are very similar to those of the lanthanides whatever range of oxidation states the actinides display, they always have -1-3 as one of them. Moreover, in the lanthanides, the element gado-... 

The three series of elements arising from the filling of the 3d, 4d and 5d shells, and situated in the periodic table following the alkaline earth metals, are commonly described as transition elements , though this term is sometimes also extended to include the lanthanide and actinide (or inner transition) elements. They exhibit a number of characteristic properties which together distinguish them from other groups of elements ... 

Between barium (Group 2, element 56) and lutetium (Group 3, element 71), the 4f orbitals fill with electrons, giving rise to the lanthanides, a set of 14 metals named for lanthanum, the first member of the series. The lanthanides are also called the rare earths, although except for promethium they are not particularly rare. Between radium (Group 2, element 88) and lawrenclum (Group 3, element 103), are the 14 actinides, named for the first member of the set, actinium. The lanthanides and actinides are also known as the inner transition metals. 

Symbol Am Atomic Number 95 Atomic Weight 243.0614 an inner-transition, actinide series, radioactive man-made element electron configuration ... 

Symbol Lr atomic number 103 atomic weight 262 a transuranium inner-transition actinide series element a synthetic radioactive element electron configuration [RnjTs b/ Sdi valence +3 six isotopes of masses 255 to 260 have been synthesized longest-lived known isotope Lr-260 has half-life of 3 minutes. 

Symbol Md atomic number 101 atomic weight (most stable isotope) 257 a man-made radioactive transuranium element an inner-transition element of actinide series electron configuration [Rn]5/i37s2 valence +2, -i-3. Isotopes, half-lives and their decay modes are ... 

Symbol Pa atomic number 91 atomic weight 231.04 an actinide series radioactive element an inner-transition metal electron configuration [Rn]5/26di7s2 valence states +4 and +5 atomic radius 1.63A (for coordination number 12) twenty-two isotopes are known in the mass range 215-218,... 

Tucked into the periodic table between lanthanum (atomic number 57) and hafnium (atomic number 72) are the lanthanides. In this series of 14 metallic elements, the seven 4/orbitals are progressively filled, as shown in Figure 5.17 (page 185). Following actinium (atomic number 89) is a second series of 14 elements, the actinides, in which the 5f subshell is progressively filled. The lanthanides and actinides together comprise thef-block elements, or inner transition elements. 

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 one another 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 one another in steps of 1. The inner transition elements mostly form oxidation states of +3, but the first part of the actinide series acts more as transition elements and the elements have maximum oxidation numbers that increase from +4 for Th to +6 for U. These generalizations are not absolute rules, but allow students to make educated guesses about possible compound formation without exhaustive memorization. These possibilities are illustrated in Fig. 14-1. 

The chemistry of the lighter actinides from thorium to americium, all being available in substantial quantities, is now well understood. In the - -4, or higher oxidation states, these elements are best considered as an inner transition series. Their chemistry shows both horizontal similarities within the actinide group and to a lesser degree, some vertical similarities with the group 4, 5, and 6 d-transition elements. All of the actinides in their +3 oxidation states behave in much the same way as the lanthanides. The chemistry of the actinides is reviewed within this context and compared with the corresponding lanthanides. 

The lanthanides, elements 58 through 71, constitute a so-called inner transition series, as do the actinides, elements 90 through 103. Scandium (21) and yttrium (39), together with the lanthanides, are traditionally referred to as the rare earth elements. The lanthanides, with 3+ ions and decreasing radii, show strong ionic bonding and weaker covalent bonding characteristics. As discussed below, the lanthanides tend to exhibit hard sphere or A-type behavior in their coordination compounds. 

The group B elements, or transition elements, are divided into transition metals and inner transition metals. The two sets of inner transition metals, known as the lanthanide and actinide series, are located along the bottom of the periodic table. The rest of the group B elements make up the transition metals. Elements from the lanthanide series are used extensively as phosphors, substances that emit light when struck by electrons. The How It Works at the end of the chapter explains more about phosphors and how images are formed on a television screen. 

The inner transition metals are divided into two groups the period 6 lanthanide series and the period 7 actinide series. 

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 Period 6 inner transition series fills the 4/orbitals and consists of the lanthanides (or rare earths), so called because they occur after and are similar to lanthanum. The other inner transition series holds the actinides, which fill the 5/orbitals that appear in Period 7 after actinium (Ac Z = 89). In both series, the (71 — 2)f orbitals are filled, after which filling of the (71 — l)r/ orbitals proceeds. Period 6 ends with the filling of the 6/7 orbitals as in other /7-block elements. Period 7 is incomplete because only two elements with Ip electrons have been confirmed at this time. 

All nuclides with Z > 83 are unstable. Bismuth-209 is the heaviest stable nuclide. Therefore, the largest members of Groups 1A(1), 2A(2), 4A(14), 6A(16), 7A(17), and 8A(18) are radioactive, as are all the actinides (the 5/inner-transition elements) and the elements of the fourth rf-block transition series (Period 7). 

The main transition elements include four series of d-block elements with atomic numbers between 21-30, 39-48, 72-80, and 104-109. The inner transition elements include the f-block (rare earth) elements in the lanthanide series (atomic numbers 57-71) and actinide series (atomic numbers 89-103.) All are metals. 

Inner transition elements include the lanthanide series and actinide series. Elements in these series have incomplete f sublevels. 

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