The Reduction of Elemental Chalcogens and Their Derivatives by Divalent Lanthanide Complexes
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Additional Teacher Background Chapter 4 Lesson 3, P. 295
Additional Teacher Background Chapter 4 Lesson 3, p. 295 What determines the shape of the standard periodic table? One common question about the periodic table is why it has its distinctive shape. There are actu- ally many different ways to represent the periodic table including circular, spiral, and 3-D. But in most cases, it is shown as a basically horizontal chart with the elements making up a certain num- ber of rows and columns. In this view, the table is not a symmetrical rectangular chart but seems to have steps or pieces missing. The key to understanding the shape of the periodic table is to recognize that the characteristics of the atoms themselves and their relationships to one another determine the shape and patterns of the table. ©2011 American Chemical Society Middle School Chemistry Unit 303 A helpful starting point for explaining the shape of the periodic table is to look closely at the structure of the atoms themselves. You can see some important characteristics of atoms by look- ing at the chart of energy level diagrams. Remember that an energy level is a region around an atom’s nucleus that can hold a certain number of electrons. The chart shows the number of energy levels for each element as concentric shaded rings. It also shows the number of protons (atomic number) for each element under the element’s name. The electrons, which equal the number of protons, are shown as dots within the energy levels. The relationship between atomic number, energy levels, and the way electrons fill these levels determines the shape of the standard periodic table. -
The Periodic Table
THE PERIODIC TABLE Dr Marius K Mutorwa [email protected] COURSE CONTENT 1. History of the atom 2. Sub-atomic Particles protons, electrons and neutrons 3. Atomic number and Mass number 4. Isotopes and Ions 5. Periodic Table Groups and Periods 6. Properties of metals and non-metals 7. Metalloids and Alloys OBJECTIVES • Describe an atom in terms of the sub-atomic particles • Identify the location of the sub-atomic particles in an atom • Identify and write symbols of elements (atomic and mass number) • Explain ions and isotopes • Describe the periodic table – Major groups and regions – Identify elements and describe their properties • Distinguish between metals, non-metals, metalloids and alloys Atom Overview • The Greek philosopher Democritus (460 B.C. – 370 B.C.) was among the first to suggest the existence of atoms (from the Greek word “atomos”) – He believed that atoms were indivisible and indestructible – His ideas did agree with later scientific theory, but did not explain chemical behavior, and was not based on the scientific method – but just philosophy John Dalton(1766-1844) In 1803, he proposed : 1. All matter is composed of atoms. 2. Atoms cannot be created or destroyed. 3. All the atoms of an element are identical. 4. The atoms of different elements are different. 5. When chemical reactions take place, atoms of different elements join together to form compounds. J.J.Thomson (1856-1940) 1. Proposed the first model of the atom. 2. 1897- Thomson discovered the electron (negatively- charged) – cathode rays 3. Thomson suggested that an atom is a positively- charged sphere with electrons embedded in it. -
Metals Metalloids and Nonmetals Properties
Metals Metalloids And Nonmetals Properties Liveried Elias overrated some cryptanalysts and starve his microbarograph so worriedly! Palpitant or bandy, Spud never ozonizing any sitcoms! Shakable Mic sometimes mobilities any carefulness veer gracefully. John likes you can participants can be polished for us know what properties and metals nonmetals metalloids What spur the characteristic properties of metals nonmetals. Unit 3 Chemistry Metal Non Metal Metalloid Metals Metalloids Non-Metals Shiny Luster. Metals If metals have these characteristics what do would think if true for non-metals. Classifying Metals Non-Metals and Metalloids. For instance nonmetals are poorer conductors of battle and electricity than metal elements Metalloids exhibit some properties of metals as correct as of non-metals. Metals Metalloids and Nonmetals Course Hero. Metals Nonmetals and Metalloids Virginia Department of. Properties of metalloids list Just Hatched. Pin on ScienceDoodads-TPT Products Pinterest. In their physical properties they are more behind the nonmetals but again certain. Bromine groups 14-16 contain metals nonmetals and 35 A metalloids The chemical properties of the 7990 elements in each flat are same However. METALS NONMETALS AND METALLOIDS LESSON PLAN. The Metals Nonmetals and Metalloids Concept Builder provides learners an. Metalloids soil chemistry and prod environment PubMed. Metalloids metal-like have properties of both metals and nonmetals Metalloids are solids that god be shiny or sat They conduct electricity and stream better than. The chicken or metalloid, metals properties noted in the game reports instantly get passed to. Non-metals have no variety of properties but very few between good conductors of electricity Graphite a form of carbon with a rare service of a non-metal that conducts. -
TEK 8.5C: Periodic Table
Name: Teacher: Pd. Date: TEK 8.5C: Periodic Table TEK 8.5C: Interpret the arrangement of the Periodic Table, including groups and periods, to explain how properties are used to classify elements. Elements and the Periodic Table An element is a substance that cannot be separated into simpler substances by physical or chemical means. An element is already in its simplest form. The smallest piece of an element that still has the properties of that element is called an atom. An element is a pure substance, containing only one kind of atom. The Periodic Table of Elements is a list of all the elements that have been discovered and named, with each element listed in its own element square. Elements are represented on the Periodic Table by a one or two letter symbol, and its name, atomic number and atomic mass. The Periodic Table & Atomic Structure The elements are listed on the Periodic Table in atomic number order, starting at the upper left corner and then moving from the left to right and top to bottom, just as the words of a paragraph are read. The element’s atomic number is based on the number of protons in each atom of that element. In electrically neutral atoms, the atomic number also represents the number of electrons in each atom of that element. For example, the atomic number for neon (Ne) is 10, which means that each atom of neon has 10 protons and 10 electrons. Magnesium (Mg) has an atomic number of 12, which means it has 12 protons and 12 electrons. -
Modeling the Shape of Ions in Pyrite-Type Crystals
Crystals 2014, 4, 390-403; doi:10.3390/cryst4030390 OPEN ACCESS crystals ISSN 2073-4352 www.mdpi.com/journal/crystals Article Modeling the Shape of Ions in Pyrite-Type Crystals Mario Birkholz IHP, Im Technologiepark 25, 15236 Frankfurt (Oder), Germany; E-Mail: [email protected]; Tel.: +49-335-56250 Received: 13 April 2014; in revised form: 22 August 2014 / Accepted: 26 August 2014 / Published: 3 September 2014 Abstract: The geometrical shape of ions in crystals and the concept of ionic radii are re-considered. The re-investigation is motivated by the fact that a spherical modelling is justified for p valence shell ions on cubic lattice sites only. For the majority of point groups, however, the ionic radius must be assumed to be an anisotropic quantity. An appropriate modelling of p valence ions then has to be performed by ellipsoids. The approach is tested for pyrite-structured dichalcogenides MX2, with chalcogen ions X = O, S, Se and Te. The latter are found to exhibit the shape of ellipsoids being compressed along the <111> symmetry axes, with two radii r|| and describing their spatial extension. Based on this ansatz, accurate interatomic M–X distances can be derived and a consistent geometrical model emerges for pyrite-structured compounds. Remarkably, the volumes of chalcogen ions are found to vary only little in different MX2 compounds, suggesting the ionic volume rather than the ionic radius to behave as a crystal-chemical constant. Keywords: ionic radius; ionic shape; bonding distance; ionic volume; pyrite-type compounds; di-chalcogenides; di-oxides; di-sulfides; di-selenides; di-tellurides 1. -
Of the Periodic Table
of the Periodic Table teacher notes Give your students a visual introduction to the families of the periodic table! This product includes eight mini- posters, one for each of the element families on the main group of the periodic table: Alkali Metals, Alkaline Earth Metals, Boron/Aluminum Group (Icosagens), Carbon Group (Crystallogens), Nitrogen Group (Pnictogens), Oxygen Group (Chalcogens), Halogens, and Noble Gases. The mini-posters give overview information about the family as well as a visual of where on the periodic table the family is located and a diagram of an atom of that family highlighting the number of valence electrons. Also included is the student packet, which is broken into the eight families and asks for specific information that students will find on the mini-posters. The students are also directed to color each family with a specific color on the blank graphic organizer at the end of their packet and they go to the fantastic interactive table at www.periodictable.com to learn even more about the elements in each family. Furthermore, there is a section for students to conduct their own research on the element of hydrogen, which does not belong to a family. When I use this activity, I print two of each mini-poster in color (pages 8 through 15 of this file), laminate them, and lay them on a big table. I have students work in partners to read about each family, one at a time, and complete that section of the student packet (pages 16 through 21 of this file). When they finish, they bring the mini-poster back to the table for another group to use. -
A Note on Radioactive Materials and Their Measurements Elements Are
A NOTE ON RADIOACTIVE MATERIALS AND THEIR MEASUREMENTS Elements are placed in the periodic table of elements according to atomic number or proton number often referred to as Z. Their atomic weights are also usually indicated and can be fractional if the element in nature contains more than one isotope. Isotopes of an element all have the same atomic number, Z, but have different numbers of neu- trons. Some of these isotopes, even in naturally occurring elements, may be radioactive, and are usually given the atomic weight of the longest known isotope. Radioactive decay occurs when an unstable atom loses energy by emitting particles and gamma radiation or by spontaneously fission- ing. (Spontaneous fission is one of the natural modes of radioactive decay in which fission occurs without the addition of external energy or particles.) The activity of a radioactive sample is simply the rate of radioactive decay, expressed as the number of decays per unit time. Traditionally, the curie (Ci) was used to quantify the decay rate and was defined as the radioactivity measured for one gram of pure radium, or ~3.7 × 1010 decays per second (d/s), but the value changed as measurement techniques improved. To avoid this problem of a “chang- ing” constant, the Curie is now defined as exactly 3.7 × 1010 d/s. The becquerel (Bq), equal to one d/s, is the official SI unit (International System of Units). The roentgen R( ) is commonly used as a unit of radiation exposure to X-ray or gamma radiation, and can be roughly defined as “that quan- tity of X-ray or gamma radiation needed to produce one electrostatic unit of ionic charge in one cm3 of air under standard temperature and pressure (STP) “normal conditions”. -
A Study of the Hydration of the Alkali Metal Ions in Aqueous Solution
Article pubs.acs.org/IC A Study of the Hydration of the Alkali Metal Ions in Aqueous Solution Johan Mahler̈ and Ingmar Persson* Department of Chemistry, Swedish University of Agricultural Sciences, P.O. Box 7015, SE-750 07 Uppsala, Sweden *S Supporting Information ABSTRACT: The hydration of the alkali metal ions in aqueous solution has been studied by large angle X-ray scattering (LAXS) and double difference infrared spectroscopy (DDIR). The structures of the dimethyl sulfoxide solvated alkali metal ions in solution have been determined to support the studies in aqueous solution. The results of the LAXS and DDIR mea- surements show that the sodium, potassium, rubidium and cesium ions all are weakly hydrated with only a single shell of water molecules. The smaller lithium ion is more strongly hydrated, most probably with a second hydration shell present. The influence of the rubidium and cesium ions on the water structure was found to be very weak, and it was not possible to quantify this effect in a reliable way due to insufficient separation of the O−D stretching bands of partially deuterated water bound to these metal ions and the O−D stretching bands of the bulk water. Aqueous solutions of sodium, potassium and cesium iodide and cesium and lithium hydroxide have been studied by LAXS and M−O bond distances have been determined fairly accurately except for lithium. However, the number of water molecules binding to the alkali metal ions is very difficult to determine from the LAXS measurements as the number of distances and the temperature factor are strongly correlated. -
Conductive-Bridging Random Access Memory
Jana et al. Nanoscale Research Letters (2015) 10:188 DOI 10.1186/s11671-015-0880-9 NANO REVIEW Open Access Conductive-bridging random access memory: challenges and opportunity for 3D architecture Debanjan Jana1, Sourav Roy1, Rajeswar Panja1, Mrinmoy Dutta1, Sheikh Ziaur Rahaman1, Rajat Mahapatra1,2 and Siddheswar Maikap1* Abstract The performances of conductive-bridging random access memory (CBRAM) have been reviewed for different switching materials such as chalcogenides, oxides, and bilayers in different structures. The structure consists of an inert electrode and one oxidized electrode of copper (Cu) or silver (Ag). The switching mechanism is the formation/dissolution of a metallic filament in the switching materials under external bias. However, the growth dynamics of the metallic filament in different switching materials are still debated. All CBRAM devices are switching under an operation current of 0.1 μAto 1mA,andanoperationvoltageof±2Visalsoneeded.Thedevice can reach a low current of 5 pA; however, current compliance-dependent reliability is a challenging issue. Although a chalcogenide-based material has opportunity to have better endurance as compared to an oxide-based material, data retention and integration with the complementary metal-oxide-semiconductor (CMOS) process are also issues. Devices with bilayer switching materials show better resistive switching characteristics as compared to those with a single switching layer, especially a program/erase endurance of >105 cycles with a high speed of few nanoseconds. Multi-level cell operation is possible, but the stability of the high resistance state is also an important reliability concern. These devices show a good data retention of >105 s at >85°C. However, more study is needed to achieve a 10-year guarantee of data retention for non-volatile memory application. -
Atomic and Ionic Radii of Elements 1–96 Martinrahm,*[A] Roald Hoffmann,*[A] and N
DOI:10.1002/chem.201602949 Full Paper & Elemental Radii Atomic and Ionic Radii of Elements 1–96 MartinRahm,*[a] Roald Hoffmann,*[a] and N. W. Ashcroft[b] Abstract: Atomic and cationic radii have been calculated for tive measureofthe sizes of non-interacting atoms, common- the first 96 elements, together with selected anionicradii. ly invoked in the rationalization of chemicalbonding, struc- The metric adopted is the average distance from the nucleus ture, and different properties. Remarkably,the atomic radii where the electron density falls to 0.001 electrons per bohr3, as defined in this way correlate well with van der Waals radii following earlier work by Boyd. Our radii are derived using derived from crystal structures. Arationalizationfor trends relativistic all-electron density functional theory calculations, and exceptionsinthose correlations is provided. close to the basis set limit. They offer asystematic quantita- Introduction cule,[2] but we prefer to follow through with aconsistent pic- ture, one of gauging the density in the atomic groundstate. What is the size of an atom or an ion?This question has been The attractivenessofdefining radii from the electron density anatural one to ask over the centurythat we have had good is that a) the electron density is, at least in principle, an experi- experimental metricinformation on atoms in every form of mental observable,and b) it is the electron density at the out- matter,and (more recently) reliable theory for thesesame ermost regionsofasystem that determines Pauli/exchange/ atoms. And the momentone asks this question one knows same-spinrepulsions, or attractive bondinginteractions, with that there is no unique answer.Anatom or ion coursing down achemical surrounding. -
UCLA Electronic Theses and Dissertations
UCLA UCLA Electronic Theses and Dissertations Title Electrochemical Performance of Titanium Disulfide and Molybdenum Disulfide Nanoplatelets Permalink https://escholarship.org/uc/item/73h6h1z6 Author Siordia, Andrew F. Publication Date 2016 Peer reviewed|Thesis/dissertation eScholarship.org Powered by the California Digital Library University of California UNIVERSITY OF CALIFORNIA Los Angeles Electrochemical Performance of Titanium Disulfide and Molybdenum Disulfide Nanoplatelets A thesis submitted in partial satisfaction of the requirements of the degree Master of Science in Materials Science and Engineering by Andrew Francisco Siordia 2016 ABSTRACT OF THESIS Electrochemical Performance of Titanium Disulfide and Molybdenum Disulfide Nanoplatelets by Andrew Francisco Siordia Master of Science in Materials Science and Engineering University of California, Los Angeles, 2016 Professor Bruce S. Dunn, Chair Single layer crystalline materials, often termed two-dimension (2D) materials, have quickly become a popular topic of research interest due to their extraordinary properties. The intrinsic electrical, mechanical, and optical properties of graphene were found to be remarkably distinct from graphite, its bulk counterpart. In conjunction with newfound processing techniques, there is renewed interest in elucidating the structure-property relationships of other 2D materials ii like the transition metal dichalcogenides (TMDCs). The energy storage capability of 2D nanoplatelets of TiS2 and MoS2 are studied here providing a contrast with investigations of corresponding bulk materials in the early 1970s. TiS2 was synthesized into nanoplatelets using a hot injection route which provided a capacity of ~143mAhg-1 from thin film electrodes as determined by cyclic voltammetry measurements. Phase identification using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy to complement the electrochemical performance and impurity identification is presented. -
L. Arulmurugan, M. Ilangkumaran " Experimental Study on Graphene/Transition Metal Chalcogenide Based Energy Storage and Conversion
Journal of Ovonic Research Vol. 16, No. 4, July - August 2020, p. 197 - 211 EXPERIMENTAL STUDY ON GRAPHENE/TRANSITION METAL CHALCOGENIDE BASED ENERGY STORAGE AND CONVERSION L. ARULMURUGANa, *, M. ILANGKUMARANb, aDepartment of Electronics and Communication Engineering, Bannari Amman Institute of Technology, Sathyamangalam, Erode, Tamilnadu, India bDepartment of Mechatronics Engineering, K S Rangasamy College of Technology, Tiruchengode, Tamilnadu, India The ever-increasing energy demand and the shortage of fossil fuels force the researchers to do research on utilization and conversion of renewable energy sources. In Recent years, the graphene and Transition Metal Chalcogenide (TMC) based Phase Change material (PCM) have been reviewed towards the future energy storage and energy conversion. This PCM is considered as a promising pathway to alleviate the energy crisis. The TMC material is considered as an emerging material due to their optoelectronic behavior and stability of the material. Moreover, the integration of TMC with graphene, significantly improve the performance of the system. The storage of solar energy in the form of sensible and latent heat has become an important aspect of energy management. To improve the performance of domestic solar water heater system, the vertical spiral and cylindrical heat exchanger is designed. The spiral module and cylindrical modules filled with and without PCM are analyzed and the obtained results are compared with each other. The results show that the spiral and cylindrical heat exchanger filled with PCM store and release the thermal energy efficiently and it performs the desired functions than the without PCM module. (Received April 28, 2020; Accepted July 14, 2020) Keywords: Graphene/transition metal chalcogenide, Phase change material, Thermal management, Heat exchanger, Spiral and cylindrical module 1.