Scandium, actinium

In str. ScF3 — fiame of oct. with common vertex, ScHal3 — isostr. FeCls, in gas — triangles (d s) 

MtScFj, M3SCF6, KSC2F7, chains of pentag. bipyr. 

NaCl — str. type SeC SC4C3 ScH2 — CaF2 str, type 

Turova, Inorganic Chemistry in Tables, DOI 10.1007/978-3-642-20487-6 26, Springer-Verlag Berlin Heidelberg 2011 

LaF3 stetype AcQs, UCI3 ste type AcBt3, UCI3 str. type ACI3, - 

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Stevenson, P. C. and Nervik, W. C. (1961). The Radiochemistry of the Rare Earths, Scandium, Yttrium and Actinium, Report No. NAS-NS-3020 (National Technical Information Service, Springfield, Virginia). 

Scandium, Sc yttrium, Y lanthanum, La trivalent lanthanides, Ln actinium, Ac ... 

The 3rd group of the Periodic Table (the 1st column within the block of the transition elements) contains the metals scandium, yttrium, lanthanum, and actinium. Lanthanum (atomic number 57) may be considered the earliest member of the family of metals, called lanthanides (general symbol Ln), forming, inside the principal transition series, an inner transition series (up to atomic number 71). Scandium and yttrium together with the lanthanides are also called rare earth metals (general symbol R). 

Each d subshell consists of five orbitals and can accommodate 10 electrons, so each transition series consists of 10 elements. The first series extends from scandium through zinc and includes many familiar metals, such as chromium, iron, and copper. The second series runs from yttrium through cadmium, and the third series runs from lanthanum through mercury. In addition, there is a fourth transition series made up of actinium through the recently discovered and as yet unnamed element 112. 

The Group 3 elements are scandium, yttrium, and lanthanum. Strictly speaking actinium should also be included, but it is the general practice to associate it with the elements that follow it (the actinides) and treat them all separately, as we do in this book in Chapter 20. 

Series on Rajdiochemistry, National Academy of Sciences. Reports available from Office of Technical Services, Department of Commerce, Washington, D C. P. C. Stevenson and W. E. Nervik, Actinium (with scandium, yttrium, rare earths), NAS-NS-3020 E. Hyde, Thorium, NAS-NS 3004 H. W. Kirby, Protactinium, NAS-NS-3016 ]. E. Gindler, Uranium, NAS-NS-3030 G. A. Burney and R M. Harbour, Neptunium, NAS-NS-3060 G. H. Coleman and R. W. Hoff, Plutonium, NAS-NS-3058 R. A. Peimeman and R. K Keenan, Americium and Curium,... 

FIGURE 30 A medium-long form and long form depiction of the 14CeTh periodic table. In this representation, the f-block consists of 14 groups of f-elements with cerium (Ce) and thorium (Th) as the first representatives of each row and lutetium (Lu) and lawrencium (Lr) as the last ones. Lanthanum (La) and actinium (Ac) are accommodated as d-block elements in group 3 (NIB) of the periodic table, below scandium (Sc) and yttrium (Y). The d-block has been torn apart in the long form, due to the insertion of the f-block. 

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. 

Actinium is the third element in Row 7 of the periodic table, a chart that shows how the chemical elements are related to each other. Some chemists place it in Group 3 (IIIB), with scandium and yttrium. Other chemists call it the first member of the actinoids. The actinoids are the 15 elements that make up Row 7 of the periodic table after radium. They have atomic numbers from 89 to 103 and are all radioactive. A radioactive atom is unstable and tends to throw off particles and emit energy in order to become stable. Either way of classifying actinium is acceptable to most chemists. 

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