DOCSLIB.ORG

What Are D Block Elements?

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
What Are D Block Elements? d and f block element XII class D block elements are the elements which can be found from the third group to the twelfth group of the modern periodic table. The valence electrons of these elements fall under the d orbital. D block elements are also referred to as transition elements or transition metals. The first three rows of the d block elements which correspond to the 3d, 4d, and 5d orbitals respectively are given in the below article. Table of Content Position D Block as Transition Element Electronic Configuration Atomic and Ionic Radii Properties Oxidation States Formation of Coloured Ions Alloy Formation Important Compounds What are d Block Elements? Elements having electrons (1 to 10) present in the d-orbital of the penultimate energy level and in the outer most „s‟ orbital (1-2) are d block elements. Although electrons do not fill up „d‟ orbital in the group 12 metals, their chemistry is similar in many ways to that of the preceding groups, and so considered as d block elements. These elements typically display metallic qualities such as malleability and ductility, high values of electrical conductivity and thermal conductivity, and good tensile strength. There are four series in the d block corresponding to the filling up of 3d, 4d, 5d or 6d orbitals. 3d- Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn 4d- Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd 5d- La, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg 6d- incomplete. There are 10 elements filling up the „d‟ orbital in each series. ⇒ Also Read F Block Elements Actinides Position of d Block Elements in Periodic Table D block elements, occupy columns 3 to 12 and may have atoms of elements with completely filled „d‟ orbital. IUPAC defines a transition metal as “an element whose atom or its cations has a partially filled d sub-shell. Why d Block Elements are called Transition Elements? Transition elements occupy groups 4–11. Scandium and yttrium of group 3, having a partially filled d subshell in the metallic state also are considered as transitions elements. Elements like Zn, CD and Hg of the 12 column of the d block have completely filled d-orbital and hence are not considered as transition elements. Transition Elements are so named, indicating their positioning and transition of properties between, s and p block elements. So, all the transition metals are d block elements but all d block elements are not transition elements. Properties of Transition Metals Electrons added to the „d‟ sub-orbitals that lie between their (n+1) s and (n+1) p sub- orbitals. Placed between s and p block elements in the periodic table. Properties between s and p-block elements. Electronic Configuration of d Block Elements D block Elements have a general electronic configuration of (n-1)d 1-10ns 1-2. These elements can find stability in half-filled orbitals and completely filled d orbitals. An example of this would be the electronic configuration of chromium, which has half filled d and s orbitals in its configuration – 3d54s1. The electronic configuration of copper is another such example. Copper displays an electronic configuration of 3d104s1 and not 3d94s2. This can be attributed to the relative stability of the completely filled d orbital. Zinc, Mercury, Cadmium, and Copernicium exhibit completely filled orbitals in their ground states and in their general oxidation states as well. For this reason, these metals are not considered as transition elements whereas the others are d block elements. The electronic configuration for period 4, transition elements is (Ar) 4s 1-2 3d 1-10 The electronic configuration for period 5, transition elements is (Kr) 5s 1-2 4d 1-10 The electronic configuration for period 6, transition elements is (Xe) 4s 1-2 3d 1-10 Along the period, from left to right, electrons are added to the 3d subshell as per the Aufbau principle and Hund‟s rule of multiplicity. 1st transition series Sc Ti V Cr Mn Fe Co Ni Cu Zn 4s23d1 4s23d2 4s23d3 4s13d5 4s23d5 4s23d6 4s23d7 4s23d8 4s13d10 4s23d10 2nd transition series Y Zr Nb Mo Tc Ru Rh Pd Ag Cd 5s24d1 5s24d2 5s14d4 5s14d5 5s24d5 5s14d7 5s14d8 5s04d10 5s14d10 5s24d10 3rd transition series La Hf Ta W Re Os Ir Pt Au Hg 6s25d1 6s25d2 6s25d3 6s25d4 6s25d5 6s25d6 6s25d7 6s15d9 6s15d10 6s25d10 Anomalies do occur in all the series, which can be explained from the following considerations. The energy gap between the ns and (n-1) d orbitals Pairing energy for the electrons in s-orbital Stability of half-filled orbitals to the partly filled orbitals. Chromium has 4s13d5 electron configuration rather than the 4s23d4 configuration and copper 4s13d10 rather than 4s23d9. These anomalies in the first transition series can be understood from the stability of half-filled orbitals compared to the partly filled orbitals. In the second series transition metals, from niobium, electron presence in d orbitals appears to be preferred than being shared in s orbitals. Between the available s and d orbitals, the electron can either go for sharing in s-orbital or excited to d-orbital. Obviously, the choice depends on the repulsive energy it has overcome on sharing and the energy gap between the s and d-orbitals. In the second series, s and d-orbital have the almost same energy, because of which electrons prefer to occupy the d-orbital. So from niobium, s-orbital has mostly only one electron. Third series transition metals, on the other hand, has more paired s configuration even at the expense of half-filled orbitals (Tungsten- 6s25d4). This series comes after filling up of 4f orbitals and resulting lanthanide contraction. The reduced size results in high shielding of d orbitals by the „f‟ electron. This shielding increases the energy gap between the s and 5d orbitals such that pairing energy is less than the excitation. Excitation of the electron does not take place in tungsten, in spite of the stability possible because of half-filled orbitals. Atomic and Ionic Radii of d Block Elements Metallic Radii of 1st, 2nd, and 3rd Row Transition Metals Atomic and ionic radii of elements of all three-transition series Decreases rapidly, from column 3 to 6 Remains steady, from column 7 to 10 and Start increasing from column 11 to 12. For example, in the first transition series, atomic radii, the decrease is more from Sc to Cr (group 3 to 6 ), is almost same for Mn, Fe, Co, Ni (group 7,8 9 &10) and increase in cu and Zn. The larger decrease in atomic radii, in column 3 to 6 elements is due to the increase in effective nuclear charge but poor shielding because of the smaller number of d-electrons. In elements of column 7 to 10 increasing effective nuclear charge is balanced by the repulsion between the shared d electrons so that radii remain the same. In the case of 11 and 12 columns elements, the d orbital is full with ten electrons and shield the electrons present in the higher s-orbital. So, group 11 &12 elements like Cu & Zn have bigger size than its earlier elements in the block. Since electrons occupy a higher orbital, radii of the third series are to be more than the second series elements. But radii of both series are almost the same. In the third series elements, 5d orbitals are filled only after the filling up of 4f orbitals, which increases the effective nuclear charge by 14 units. This higher nuclear charge leads to the larger shrinkage of radii known as Lanthanide contraction. Increase in radii due to the higher orbital will be effectively neutralized by the increase the nuclear effective charge. So, radii of second and third series elements have same atomic radii. For example, Niobium and hafnium have almost the same atomic radii. Properties of d Block Elements Ionization Energy of d Block Elements Ionization energy is the energy needed to remove the valence electron from the atom/ion and is directly related to the force of attraction on the electron. Hence larger the nuclear charge and smaller the radii of the electron larger will be the ionization energy (IE). Ionization Energy also will be more for half-filled and fully filled orbitals. Ionization Energy of the d block elements is larger than s-block and smaller than the p-block elements, between which, they are placed. In the first series, except chromium and copper first Ionization Energy involves removal from filled s-orbital. Among them, Ionization Energy of d block elements increases with the increase in atomic number up to Fe. In Co and Ni, increasing sharing of d-electrons compensate for the atomic number increase resulting in the decrease of Ionization Energy. Copper and zinc show increasing IE, as s -block elements. In the second series, elements from Niobium have single electrons in the s-orbital. Hence, they show a gradual increase in IE with increasing atomic number. Palladium, on the other hand, has completed d-shell and no electron in s-shell. So, Pd shows the maximum IE. Because of lanthanide contraction, the attraction of electrons by the nuclear charge is much higher and hence IE of 5d elements are much larger than 4d and 3d. In 5d series, all elements except Pt and Au have filled s-shell. Elements from Hafnium to rhenium have same IE and after IE increases with the number of shared d-electrons such that Iridium and Gold have the maximum IE. Metallic Character D block elements show typical metallic behaviour of high tensile strength, malleability, ductility, electrical and thermal conductivity, metallic lustre and crystallize in bcc/ccp/hcp structures.
Load more

Recommended publications
  • Lanthanides & Actinides Notes
    - 1 - LANTHANIDES & ACTINIDES NOTES General Background Mnemonics Lanthanides Lanthanide Chemistry Presents No Problems Since Everyone Goes To Doctor Heyes' Excruciatingly Thorough Yearly Lectures La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Actinides Although Theorists Prefer Unusual New Proofs Able Chemists Believe Careful Experiments Find More New Laws Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr Principal Characteristics of the Rare Earth Elements 1. Occur together in nature, in minerals, e.g. monazite (a mixed rare earth phosphate). 2. Very similar chemical properties. Found combined with non-metals largely in the 3+ oxidation state, with little tendency to variable valence. 3. Small difference in solubility / complex formation etc. of M3+ are due to size effects. Traversing the series r(M3+) steadily decreases – the lanthanide contraction. Difficult to separate and differentiate, e.g. in 1911 James performed 15000 recrystallisations to get pure Tm(BrO3)3! f-Orbitals The Effective Electron Potential: • Large angular momentum for an f-orbital (l = 3). • Large centrifugal potential tends to keep the electron away from the nucleus. o Aufbau order. • Increased Z increases Coulombic attraction to a larger extent for smaller n due to a proportionately greater change in Zeff. o Reasserts Hydrogenic order. This can be viewed empirically as due to differing penetration effects. Radial Wavefunctions Pn,l2 for 4f, 5d, 6s in Ce 4f orbitals (and the atoms in general) steadily contract across the lanthanide series. Effective electron potential for the excited states of Ba {[Xe] 6s 4f} & La {[Xe] 6s 5d 4f} show a sudden change in the broadness & depth of the 4f "inner well".
    [Show full text]
  • Electronic Structure of Ytterbium(III) Solvates – a Combined Spectro
    Electronic Structure of Ytterbium( III) Solvates – A Combined Spectro- scopic and Theoretical Study Nicolaj Kofod,† Patrick Nawrocki,† Carlos Platas-Iglesias,*,‡ Thomas Just Sørensen*,† † Department of Chemistry and Nano-Science Center, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Den- mark. ‡ Centro de Investigacións Científicas Avanzadas and Departamento de Química, Universidade da Coruña, Campus da Zapateira-Rúa da Fraga 10, 15008 A Coruña, Spain ABSTRACT: The wide range of optical and magnetic properties of the lanthanide(III) ions is associated to their intricate electronic structures, which in contrast to lighter elements is characterized by strong relativistic effects and spin-orbit coupling. Nevertheless, computational methods are now capable of describing the ladder of electronic energy levels of the simpler trivalent lanthanide ions, as well as the lowest energy term of most of the series. The electronic energy levels result from electron configurations that are first split by spin-orbit coupling into groups of energy levels denoted by the corresponding Russel-Saunders terms. Each of these groups are then split by the ligand field into the actual electronic energy levels known as microstates or sometimes mJ levels. The ligand field splitting directly informs on coordination geometry, and is a valuable tool for determining structure and thus correlating the structure and properties of metal complexes in solution. The issue with lanthanide com- plexes is that the determination of complex structures from ligand field splitting remains a very challenging task. In this manuscript, the optical spectra – absorption, luminescence excitation and luminescence emission – of ytterbium(III) solvates were recorded in water, methanol, dime- thyl sulfoxide and N,N-dimethylformamide.
    [Show full text]
  • Why Isn't Hafnium a Noble Gas? Also More on the Lanthanide Contraction
    return to updates Period 6 Why Isn't Hafnium a Noble Gas? also more on the Lanthanide contraction by Miles Mathis First published March 30, 2014 This paper replaces my earlier paper on the Lanthanides After a long break, it is time I returned to the Periodic Table. Many readers probably wish I would concentrate more on one subject, or at least one area of physics or chemistry. Possibly, they think I would get more done that way. They are mistaken. I would indeed get more done in that one field, and if that is their field, of course that would satisfy them more personally. But by skipping around, I actually maximize my production. How? One, I stay fresh. I don't get bored by staying in one place too long, so my creativity stays at a peak. Two, I cross-pollinate my ideas. My readers have seen how often a discovery in one sub-field helps me in another sub-field, even when those two fields aren't adjacent. All of science (and life) is ultimately of a piece, so anything I learn anywhere will help me everywhere else. Three, being interested in a wide array of topics gives me a bigger net, and with a bigger net I am better able to capture solutions across the board. Knowledge isn't just a matter of depth, it is a matter of breadth. In philosophy classes, we were taught this as part of the hermeneutic circle: the parts feed the whole and the whole feeds back into all the parts.
    [Show full text]
  • Schematic Interpretation of Anomalies in the Physical Properties of Eu and Yb Among the Lanthanides
    International Journal of Materials Science and Applications 2017; 6(4): 165-170 http://www.sciencepublishinggroup.com/j/ijmsa doi: 10.11648/j.ijmsa.20170604.11 ISSN: 2327-2635 (Print); ISSN: 2327-2643 (Online) Schematic Interpretation of Anomalies in the Physical Properties of Eu and Yb Among the Lanthanides Yoshiharu Mae Maetech, Mimuro, Midori Ward, Saitama City, Japan Email address: [email protected] To cite this article: Yoshiharu Mae. Schematic Interpretation of Anomalies in the Physical Properties of Eu and Yb Among the Lanthanides. International Journal of Materials Science and Applications. Vol. 6, No. 4, 2017, pp. 165-170. doi: 10.11648/j.ijmsa.20170604.11 Received: May 24, 2017; Accepted: June 2, 2017; Published: June 19, 2017 Abstract: Lanthanides are the elements in 6th period and the 3rd group of the periodic table. Eu and Yb exhibit some unusual properties compared with the other lanthanides. The author has proposed a diagram to systematically illustrate the properties of the elements, by plotting the Young’s modulus on the ordinate and thermal conductivity on the abscissa. Eu and Yb have much lower Young’s moduli, and are located far from other lanthanides on the diagram. Most lanthanides have hexagonal structures. Eu, however, has a body-centered cubic structure, because it is located on the extension of the curve of alkali metals. Yb has a face-centered cubic (fcc) structure, because it is located on the curve of fcc metals. The positions of Eu and Yb on the diagram are thought to act as a bridge between the lanthanides and other adjacent element groups.
    [Show full text]
  • Lanthanides.Pdf
    Lanthanides [A] LANTHANIDES : 4f block elements Definition: The f- block (inner transition) elements containing partially filled 4f-subshells are known as Lanthanides or Lanthanones because of their close similarities with element lanthanum (atomic no: 57). The fourteen elements from atomic no: 58 to 71 constitute lanthanides. Nos. Name Symbol Electronic configuration 0 1 2 1. Lanthanum La57 [Xe] 4f 5d 6s 2 0 2 2. Cerium Ce58 [Xe] 4f 5d 6s 3 0 2 3. Praseodymium Pr59 [Xe] 4f 5d 6s 4 0 2 4. Neodymium Nd60 [Xe] 4f 5d 6s 5 0 2 5. Promethium Pm61 [Xe]4f 5d 6s 6 0 2 6. Samarium Sm62 [Xe]4f 5d 6s 7 0 2 7. Europium Eu63 [Xe] 4f 5d 6s 7 1 2 8. Gadolinium Gd64 [Xe] 4f 5d 6s 9 0 2 9. Terbium Tb65 [Xe] 4f 5d 6s 10 0 2 10. Dysprosium Dy66 [Xe] 4f 5d 6s 11 0 2 11. Holmium Ho67 [Xe] 4f 5d 6s 12 0 2 12. Erbium Er68 [Xe] 4f 5d 6s 13 0 2 13. Thulium Tm69 [Xe] 4f 5d 6s 14 0 2 14. Ytterbium Yb70 [Xe] 4f 5d 6s 14 1 2 15. Lutetium Lu71 [Xe] 4f 5d 6s From the above electronic configuration it can be seen that at La 5d orbital is singly occupied but after La further filling of 5d orbital is discontinued. As the nuclear charge increases by one unit from La to Ce, 4f orbitals were higher in energy upto Lu, fall slightly below the 5d level 4f- orbitals, therefore begin to fill and are completely filled up to Lu, before filling of 5d orbital is resumed.
    [Show full text]
  • Lanthanide Contraction Lanthanide Contraction W Urood A
    Lanthanide contraction Wurood A. Jaafar, Enass J. Waheed, Zainab A. Jabarah* Department of Chemistry, College of Education for Pure Science (Ibn Al-Haitham), University of Baghdad, Baghdad, Iraq. *Basic Science Division, College of Agriculture Engineering Science, University of Baghdad, Baghdad, Iraq. The lanthanides-or lanthanids, as they are sometimes called- are, strictly, the fourteen elements that follow lanthanum in the periodic table and in which the fourteen 4f electrons are successively added to the lanthanum configuration. Since these 4f relatively uninvolved in bonding, the main result is that all these highly electropositive elements have; as their prime oxidation state, the M+3 ion. The lanthanide series consist of the 14 elements, with atomic numbers 58 through 71…… Lanthanide contraction was used in discussing the elements of the third transition series, since it has certain important effects on their properties. It consists of a significant and steady decrease in the size of the atoms and ions with increasing atomic number, that is, La has the greatest, and Lu the smallest radius. The effect results from poor shielding of nuclear charge (nuclear attractive force on electrons) by 4f electrons; the 6s electrons are drawn towards the nucleus, thus resulting in a smaller atomic radius. In single-electron atoms, the average separation of an electron from the nucleus is determined by the subshell it belongs to, and decreases with increasing charge on the nucleus; this in turn leads to a decrease in atomic radius. In multi-electron atoms, the decrease in radius brought about by an increase in nuclear charge is partially offset by increasing electrostatic repulsion among electrons.
    [Show full text]
  • Periodic Table 1 Periodic Table
    Periodic table 1 Periodic table This article is about the table used in chemistry. For other uses, see Periodic table (disambiguation). The periodic table is a tabular arrangement of the chemical elements, organized on the basis of their atomic numbers (numbers of protons in the nucleus), electron configurations , and recurring chemical properties. Elements are presented in order of increasing atomic number, which is typically listed with the chemical symbol in each box. The standard form of the table consists of a grid of elements laid out in 18 columns and 7 Standard 18-column form of the periodic table. For the color legend, see section Layout, rows, with a double row of elements under the larger table. below that. The table can also be deconstructed into four rectangular blocks: the s-block to the left, the p-block to the right, the d-block in the middle, and the f-block below that. The rows of the table are called periods; the columns are called groups, with some of these having names such as halogens or noble gases. Since, by definition, a periodic table incorporates recurring trends, any such table can be used to derive relationships between the properties of the elements and predict the properties of new, yet to be discovered or synthesized, elements. As a result, a periodic table—whether in the standard form or some other variant—provides a useful framework for analyzing chemical behavior, and such tables are widely used in chemistry and other sciences. Although precursors exist, Dmitri Mendeleev is generally credited with the publication, in 1869, of the first widely recognized periodic table.
    [Show full text]
  • Relativistic Effects in Chemistry: More Common Than You Thought
    PC63CH03-Pyykko ARI 27 February 2012 9:31 Relativistic Effects in Chemistry: More Common Than You Thought Pekka Pyykko¨ Department of Chemistry, University of Helsinki, FI-00014 Helsinki, Finland; email: pekka.pyykko@helsinki.fi Annu. Rev. Phys. Chem. 2012.63:45-64. Downloaded from www.annualreviews.org Annu. Rev. Phys. Chem. 2012. 63:45–64 Keywords Access provided by WIB6049 - University of Freiburg on 07/13/18. For personal use only. First published online as a Review in Advance on Dirac equation, heavy-element chemistry, gold, lead-acid battery January 30, 2012 The Annual Review of Physical Chemistry is online at Abstract physchem.annualreviews.org Relativistic effects can strongly influence the chemical and physical proper- This article’s doi: ties of heavy elements and their compounds. This influence has been noted 10.1146/annurev-physchem-032511-143755 in inorganic chemistry textbooks for a couple of decades. This review pro- Copyright c 2012 by Annual Reviews. vides both traditional and new examples of these effects, including the special All rights reserved properties of gold, lead-acid and mercury batteries, the shapes of gold and 0066-426X/12/0505-0045$20.00 thallium clusters, heavy-atom shifts in NMR, topological insulators, and certain specific heats. 45 PC63CH03-Pyykko ARI 27 February 2012 9:31 1. INTRODUCTION Relativistic effects are important for fast-moving particles. Because the average speeds of valence electrons are low, it was originally thought [in fact by Dirac (1) himself ] that relativity then was unimportant. It has now been known for a while that relativistic effects can strongly influence many chemical properties of the heavier elements (2–5).
    [Show full text]
  • Ganesh Kumar Date:- 04/03/2021 D – Block Elements
    Chemistry Study Materials for Class 12 (NCERT Based Revision Notes) Ganesh Kumar Date:- 04/03/2021 d – Block Elements GENERAL CHARACTERISTICS OF LANTHANIDES: 1. There are hard metals with high melting points. 2. Oxidation state. The lanthanides too display variable oxidation states. The characteristic and the most stable oxidation state of lanthanides is + 3 (Ln3+). This oxidation state is obtained by the loss of one 5d-electron and two 6s- electrons. Along with + 3 oxidation state, certain metals show + 2 and + 4 oxidation states so as to attain f 0, f 7 and f 14 configurations. 3. Ionic radii-Lanthanide contraction. There is a regular decrease in the size of atoms/ions with increase in atomic number as we move across from La to Lu. Thus among lanthanides, lanthanum has the largest and lutetium has the smallest radii. This slow decrease in size is known as lanthanide contraction. Cause of lanthanide contraction: The configurations of lanthanides show that the additional electron enters the 4f- sub shell. The shielding of one 4f-electron by another is very little (imperfect), being even smaller than that encountered in case of d-electrons (d-transition series). The imperfect shielding of f-electrons is due to the shape of f-orbitals which is very much diffused. Thus as the atomic number increases, the nuclear charge increases by unity of each stop, white no comparable increase in the mutual shielding effect of 4f- electrons occurs. This causes a contraction in the size of the 4f-subshell. Consequently the atomic and ionic size goes on decreasing systematically from La to Lu.
    [Show full text]
  • 1 Introduction to the Lanthanides
    SPH SPH JWBK057-01 JWBK057-Cotton December 7, 2005 19:54 Char Count= 1 Introduction to the Lanthanides By the end of this chapter you should be able to: r r understand that lanthanides differ in their properties from the s- and d-block metals; r recall characteristic properties of these elements; r appreciate reasons for their positioning in the Periodic Table; understand how the size of the lanthanide ions affects certain properties and how this can be used in the extraction and separation of the elements; r + understand how to obtain pure samples of individual Ln3 ions. 1.1 Introduction Lanthanide chemistry started in Scandinavia. In 1794 Johann Gadolin succeeded in ob- taining an ‘earth’(oxide) from a black mineral subsequently known as gadolinite; he called the earth yttria. Soon afterwards, M.H. Klaproth, J.J. Berzelius and W. Hisinger obtained ceria, another earth, from cerite. However, it was not until 1839–1843 that the Swede C.G. Mosander first separated these earths into their component oxides; thus ceria was resolved into the oxides of cerium and lanthanum and a mixed oxide ‘didymia’ (a mixture of the oxides of the metals from Pr through Gd). The original yttria was similarly separated into substances called erbia, terbia, and yttria (though some 40 years later, the first two names were to be reversed!). This kind of confusion was made worse by the fact that the newly discovered means of spectroscopic analysis permitted misidentifications, so that around 70 ‘new’ elements were erroneously claimed in the course of the century. Nor was Mendeleev’s revolutionary Periodic Table a help.
    [Show full text]
  • I Anomalous Properties of Elements I That MOW "Long Periods" of Elements
    James E. Huheey and Caroline L. Huheey I Anomalous Properties of Elements University of Maryland College Park, 20742 I that MOW"Long Periods" of Elements The phenomenon known as the lantha- difficulties in their separation are well-documented (3). nide contraction has long been appreciated as an impor- Less well-explored are the cases in which the lanthanide tant factor in determining the properties of the lan- contraction results in different properties for the post- thanide and post-lanthanide elements. Appreciation lanthanide elements (4). In general, these may be re- of this phenomenon is of obvious heuristic value with lated to greater effective nuclear charge and attraction regard to research efforts directed towards these ele- for electrons in the heavier elements. ments. In addition there is an implicit pedagogical Table I lists the ground state ionization energies (6) value that has been discussed at some length (1) and for the elements rubidium-xenon (Period Five) and which is included in most descriptive discussions of these cesium-radon (Period Six). The pre-lanthanide ele- elements. It is the purpose of this paper to examine ments cesium, barium, and lanthanum have ionization the physical nature of this phenomenon and extend the energies less than their lighter congeners as expected for concept to other parts of the periodic table. the main group elements. The effect of the addition of fourteen protons to the nucleus and fourteen poorly shielding 4f electrons is a higher ionization energy for hafnium than for zirconium. 811 of the following sixth period transition elements have higher ionization ener- gies than their lighter congeners and the trend persists as far as lead.
    [Show full text]
  • Crystal Structure of Praseodymium Carbide Iodide,[Pr14 (C2) 3]
    Z. Kristallogr. NCS 222 (2007) 9-10 / DOI 10.1524/ncrs.2007.0004 9 © by Oldenbourg Wissenschaftsverlag, München Crystal structure of praseodymium carbide iodide, [Pr14(C2)3]I20 Rafa» Wiglusz, Ingo Pantenburg and Gerd Meyer* Universität zu Köln, Institut für Anorganische Chemie, Greinstraße 6, 50939 Köln, Germany Received December 15, 2006, accepted and available on-line March 29, 2007; CSD no. 409907 Abstract Source of material C3I10Pr7, triclinic, P1 (no. 2), a = 9.604(2) Å, PrI3 was synthesized from the elements and purified by high- a b = 11.577(2) Å, c = 13.796(2) Å, = 80.05(1)°, vacuum sublimation [1]. A mixture of PrI3, Pr and C in a molar ra- 3 b = 71.87(1)°, g = 65.89(1)°, V = 1328.7 Å , Z =2, tio 1.11:1.22:1 was filled under dry-box conditions (MBraun, 2 Rgt(F) = 0.050, wRref(F ) = 0.145, T =170K. Garching, argon atmosphere) into a tantalum tube which was he- _____________ lium-arc welded and jacketed in a silica tube under reduced pres- * Correspondence author (e-mail: [email protected]) sure. The sample was heated to 1000 K, kept there for two weeks, 10 [Pr14(C2)3]I20 cooled with 10 K/h to 800 K, annealed there for another two analogues of lanthanum and cerium, oligomers of three [Pr6(C2)] weeks and finally cooled to ambient temperature with 20 K/h. octahedra sharing two common trans edges, [Pr14(C2)3]I24, which Black single crystals of [Pr14(C2)3]I20 were selected with the aid are further connected via a-i bridges with other such oligomers, of a microscope in an argon-filled dry-box and mounted in thin- see for a detailed description of the structure [8].
    [Show full text]