An Alternate Graphical Representation of Periodic Table of Chemical Elements Mohd Abubakr1, Microsoft India (R&D) Pvt
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5 Heavy Metals As Endocrine-Disrupting Chemicals
5 Heavy Metals as Endocrine-Disrupting Chemicals Cheryl A. Dyer, PHD CONTENTS 1 Introduction 2 Arsenic 3 Cadmium 4 Lead 5 Mercury 6 Uranium 7 Conclusions 1. INTRODUCTION Heavy metals are present in our environment as they formed during the earth’s birth. Their increased dispersal is a function of their usefulness during our growing dependence on industrial modification and manipulation of our environment (1,2). There is no consensus chemical definition of a heavy metal. Within the periodic table, they comprise a block of all the metals in Groups 3–16 that are in periods 4 and greater. These elements acquired the name heavy metals because they all have high densities, >5 g/cm3 (2). Their role as putative endocrine-disrupting chemicals is due to their chemistry and not their density. Their popular use in our industrial world is due to their physical, chemical, or in the case of uranium, radioactive properties. Because of the reactivity of heavy metals, small or trace amounts of elements such as iron, copper, manganese, and zinc are important in biologic processes, but at higher concentrations they often are toxic. Previous studies have demonstrated that some organic molecules, predominantly those containing phenolic or ring structures, may exhibit estrogenic mimicry through actions on the estrogen receptor. These xenoestrogens typically are non-steroidal organic chemicals released into the environment through agricultural spraying, indus- trial activities, urban waste and/or consumer products that include organochlorine pesticides, polychlorinated biphenyls, bisphenol A, phthalates, alkylphenols, and parabens (1). This definition of xenoestrogens needs to be extended, as recent investi- gations have yielded the paradoxical observation that heavy metals mimic the biologic From: Endocrine-Disrupting Chemicals: From Basic Research to Clinical Practice Edited by: A. -
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". -
The Periodic Electronegativity Table
The Periodic Electronegativity Table Jan C. A. Boeyens Unit for Advanced Study, University of Pretoria, South Africa Reprint requests to J. C. A. Boeyens. E-mail: [email protected] Z. Naturforsch. 2008, 63b, 199 – 209; received October 16, 2007 The origins and development of the electronegativity concept as an empirical construct are briefly examined, emphasizing the confusion that exists over the appropriate units in which to express this quantity. It is shown how to relate the most reliable of the empirical scales to the theoretical definition of electronegativity in terms of the quantum potential and ionization radius of the atomic valence state. The theory reflects not only the periodicity of the empirical scales, but also accounts for the related thermochemical data and serves as a basis for the calculation of interatomic interaction within molecules. The intuitive theory that relates electronegativity to the average of ionization energy and electron affinity is elucidated for the first time and used to estimate the electron affinities of those elements for which no experimental measurement is possible. Key words: Valence State, Quantum Potential, Ionization Radius Introduction electronegative elements used to be distinguished tra- ditionally [1]. Electronegativity, apart from being the most useful This theoretical notion, in one form or the other, has theoretical concept that guides the practising chemist, survived into the present, where, as will be shown, it is also the most bothersome to quantify from first prin- provides a precise definition of electronegativity. Elec- ciples. In historical context the concept developed in a tronegativity scales that fail to reflect the periodicity of natural way from the early distinction between antag- the L-M curve will be considered inappropriate. -
IA Metals: Alkali Metals
IA Metals: Alkali Metals INTRODUCTION: The alkali metals are a group in the periodic table consisting of the chemical elements lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs). You should remember that there is a separate group called the alkaline earth metals in Group Two. They are a very different family, even though they have a similar name. The seventh member of alkali metals group – francium, is radioactive and so rare that only 20 atoms of francium may exist on Earth at any given moment. The term alkali is derived from an Arabic word meaning “ashes.” PHYSICAL PROPERTIES: Shiny Soft (They can all be cut easily with a knife ) Highly reactive at standard temperature and pressure Because of their high reactivity, they must be stored under oil to prevent reaction with air Their density increases as we move from Li to F White/metal coloured Very good conductors of heat and electricity Have the ability to impart colour to the flame. This property of alkali metals is used in their identification. CHEMICAL PROPERTIES: The atom of any given alkali metal has only one valence electron. The chemical reactivity of alkali metals increase as we move from the top to the bottom of the group. Like any other metals, ionization potential is very low. In fact, alkali metals have the lowest ionization potential among the elements of any given period of the periodic table. Any alkali metal when comes in contact with air or oxygen, starts burning and oxides are formed in the process. At the end of the chemical reaction, lithium gives lithium monoxide (LiO), sodium gives sodium peroxide (Na2O2) and other alkali metals give superoxides. -
Suppression Mechanisms of Alkali Metal Compounds
SUPPRESSION MECHANISMS OF ALKALI METAL COMPOUNDS Bradley A. Williams and James W. Fleming Chemistry Division, Code 61x5 US Naval Research Lnhoratory Washington, DC 20375-5342, USA INTRODUCTION Alkali metal compounds, particularly those of sodium and potassium, are widely used as fire suppressants. Of particular note is that small NuHCOi particles have been found to be 2-4 times more effective by mass than Halon 1301 in extinguishing both eountertlow flames [ I] and cup- burner flames [?]. Furthermore, studies in our laboratory have found that potassium bicarbonate is some 2.5 times more efficient by weight at suppression than sodium bicarhonatc. The primary limitation associated with the use of alkali metal compounds is dispersal. since all known compounds have very low volatility and must he delivered to the fire either as powders or in (usually aqueous) solution. Although powders based on alkali metals have been used for many years, their mode of effective- ness has not generally been agreed upon. Thermal effects [3],namely, the vaporization of the particles as well as radiative energy transfer out of the flame. and both homogeneous (gas phase) and heterogeneous (surface) chemistry have been postulated as mechanisms by which alkali metals suppress fires [4]. Complicating these issues is the fact that for powders, particle size and morphology have been found to affect the suppression properties significantly [I]. In addition to sodium and potassium, other alkali metals have been studied, albeit to a consider- ably lesser extent. The general finding is that the suppression effectiveness increases with atomic weight: potassium is more effective than sodium, which is in turn more effective than lithium [4]. -
Power Sources Challenge
POWER SOURCES CHALLENGE FUSION PHYSICS! A CLEAN ENERGY Summary: What if we could harness the power of the Sun for energy here on Fusion reactions occur when two nuclei come together to form one Earth? What would it take to accomplish this feat? Is it possible? atom. The reaction that happens in the sun fuses two Hydrogen atoms together to produce Helium. It looks like this in a very simplified way: Many researchers including our Department of Energy scientists and H + H He + ENERGY. This energy can be calculated by the famous engineers are taking on this challenge! In fact, there is one DOE Laboratory Einstein equation, E = mc2. devoted to fusion physics and is committed to being at the forefront of the science of magnetic fusion energy. Each of the colliding hydrogen atoms is a different isotope of In order to understand a little more about fusion energy, you will learn about hydrogen, one deuterium and one the atom and how reactions at the atomic level produce energy. tritium. The difference in these isotopes is simply one neutron. Background: It all starts with plasma! If you need to learn more about plasma Deuterium has one proton and one physics, visit the Power Sources Challenge plasma activities. neutron, tritium has one proton and two neutrons. Look at the The Fusion Reaction that happens in the SUN looks like this: illustration—do you see how the mass of the products is less than the mass of the reactants? That is called a mass deficit and that difference in mass is converted into energy. -
The Development of the Periodic Table and Its Consequences Citation: J
Firenze University Press www.fupress.com/substantia The Development of the Periodic Table and its Consequences Citation: J. Emsley (2019) The Devel- opment of the Periodic Table and its Consequences. Substantia 3(2) Suppl. 5: 15-27. doi: 10.13128/Substantia-297 John Emsley Copyright: © 2019 J. Emsley. This is Alameda Lodge, 23a Alameda Road, Ampthill, MK45 2LA, UK an open access, peer-reviewed article E-mail: [email protected] published by Firenze University Press (http://www.fupress.com/substantia) and distributed under the terms of the Abstract. Chemistry is fortunate among the sciences in having an icon that is instant- Creative Commons Attribution License, ly recognisable around the world: the periodic table. The United Nations has deemed which permits unrestricted use, distri- 2019 to be the International Year of the Periodic Table, in commemoration of the 150th bution, and reproduction in any medi- anniversary of the first paper in which it appeared. That had been written by a Russian um, provided the original author and chemist, Dmitri Mendeleev, and was published in May 1869. Since then, there have source are credited. been many versions of the table, but one format has come to be the most widely used Data Availability Statement: All rel- and is to be seen everywhere. The route to this preferred form of the table makes an evant data are within the paper and its interesting story. Supporting Information files. Keywords. Periodic table, Mendeleev, Newlands, Deming, Seaborg. Competing Interests: The Author(s) declare(s) no conflict of interest. INTRODUCTION There are hundreds of periodic tables but the one that is widely repro- duced has the approval of the International Union of Pure and Applied Chemistry (IUPAC) and is shown in Fig.1. -
ELECTRON AFFINITY - the Electron Affinity Is the ENERGY CHANGE on Adding a Single Electron to an Atom
189 ELECTRON AFFINITY - the electron affinity is the ENERGY CHANGE on adding a single electron to an atom. - Atoms with a positive electron affinity cannot form anions. - The more negative the electron affinity, the more stable the anion formed! - General trend: As you move to the right on the periodic table, the electron affinity becomes more negative. EXCEPTIONS - Group IIA does not form anions (positive electron affinity)! valence electrons for Group IIA! period number - To add an electron, the atom must put it into a higher-energy (p) subshell. - Group VA: can form anions, but has a more POSITIVE electron affinity than IVA valence electrons for Group VA! Half-full "p" subshell! To add an electron, must start pairing! - Group VIIIA (noble gases) does not form anions full "s" and "p" subshells! 190 "MAIN" or "REPRESENTATIVE" GROUPS OF THE PERIODIC TABLE IA VIIIA 1 H He IIA IIIA IVA VA VIA VIIA 2 Li Be Read about these in B C N O F Ne Section 8.7 of the Ebbing 3 Na Mg Al Si P S Cl Ar textbook! 4 K Ca Ga Ge As Se Br Kr 5 Rb Sr In Sn Sb Te I Xe 6 Cs Ba Tl Pb Bi Po At Rn 7 Fr Ra Chalcogens Alkaline earth metals Halogens Alkali metals Noble/Inert gases 191 The representative (main) groups GROUP IA - the alkali metals valence electrons: - React with water to form HYDROXIDES alkali metals form BASES when put into water! - Alkali metal OXIDES also form bases when put into water. (This is related to METALLIC character. -
Ionization Energies Bonding: Electron Affinity Bonding
Announcements – 9/13/00 Bonding: Ionization Energies n Labs begin TODAY! n Ionization Energy (IE) n Old exams on website -quantifies the tendency of an electron to leave an atom in the gas phase: n Problem Set Solutions? n Exam #1 X (g) X+ (g) + e- DE = IE -covers matl thru this Friday (Ch 1&2) IE: -always positive (energy ADDED) -email/contact me ASAP if you have a conflict with exam time -INCR across row -DECR down a group n Demo and Quiz on Friday 1 2 Bonding: Electron Affinity Bonding: Electronegativity n Electron Affinity (EA) n Electronegativity (EN) - -quantifies ability of an atom to attract an e in -combines IE and EA terms to give the the gas phase relative ability of an atom to attract e-’s to X (g) + e- ® X- (g) -DE = EA itself when bonded to another atom EA: -it’s the energy released upon addition of an electron to an atom EN: -INCR across a row -can be positive or negative -DECR down a group - (pos: atom wants the e -Best to consider DEN for a bond neg: atom happy as an atom) 3 4 1 EN: Examples Bond Polarity: Dipole Momement n NaCl: Na EN = 0.93 n HCl d+ d- ¬ partial charges DEN = 2.23 (ionic) H – Cl Cl EN = 3.16 2.2 3.2 Polar Covalent bond: share e-, but not equally n O2: O EN = 3.44 DEN = 0 (covalent) -Quantify via: DIPOLE MOMENT (µ) n HCl: H EN = 2.2 µ = d x d Bond length (m) DEN = 0.96 (?) 1 Debye (D) Amt of displaced charge (C) Cl EN = 3.16 (polar covalent) = 3.34 x 10-30 C-m 5 6 Dipole Moment Examples Visualizing Molecules n H2O O EN = 3.44 H EN = 2.2 DEN = 1.24 CH4 -each H-O bond is polar, but does the MOLECULE have -
25 WORDS CHLORINE Chlorine, Cl, Is a Very Poisonous Green Gas That's
25 WORDS CHLORINE Chlorine, Cl, is a very poisonous green gas that's extremely reactive. It's used for sanitizing, purifying, and was used as a weapon during World War I by the Germans. But in chemistry, it is an oxidizer. Chlorine, Cl, is a green gaseous element with an atomic number of 17. This halogen is a powerful oxidant and used to produce many things, such as cleaning products. Chlorine; it's chemical symbol is Cl. Chloride is abundant in nature and necessary for life but a large amount can cause choking and and poisoning. It's mainly used for water purification but has other uses. Chlorine is a halogen and to test if it has a halogen, we use the Beilstein Copper Wire Test. It is also used to produce safe drinking water. Chlorine, atomic number seventeen, is a halogen that is found in table salt, NaCl, making it essential to life. However, pure chlorine, Cl2, is a poisonous gas, detectable at even 1 ppm. Chlorine, (Symbol Cl), belongs to the halogen family of elements, found in group 17 on the periodic table. Chlorine has an atomic number of 17 and atomic weight of 35.453. Chlorine is the 17th element on the periodic table, and is in the "Halogens" group, which has a tendency to gain one electron to form anions. Its anion can be found commonly in table salt Chlorine (symbolized Cl) is the chemical element with atomic number 17. Clorine is a powerful oxidant and is used in bleaching and disinfectants. It is a pale yellow-green gas that has a specific strong smell. -
Development of a Solvent Extraction Process for Group Actinide Recovery from Used Nuclear Fuel
THESIS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY Development of a Solvent Extraction Process for Group Actinide Recovery from Used Nuclear Fuel EMMA H. K. ANEHEIM Department of Chemical and Biological Engineering CHALMERS UNIVERSITY OF TECHNOLOGY Gothenburg, Sweden, 2012 Development of a Solvent Extraction Process for Group Actinide Recovery from Used Nuclear Fuel EMMA H. K. ANEHEIM ISBN 978-91-7385-751-2 © EMMA H. K. ANEHEIM, 2012. Doktorsavhandlingar vid Chalmers tekniska högskola Ny serie Nr 3432 ISSN 0346-718X Department of Chemical and Biological Engineering Chalmers University of Technology SE-412 96 Gothenburg Sweden Telephone + 46 (0)31-772 1000 Cover: Radiotoxicity as a function of time for the once through fuel cycle (left) compared to one P&T cycle using the GANEX process (right) (efficiencies: partitioning from Table 5.5.4, transmutation: 99.9%). Calculations performed using RadTox [HOL12]. Chalmers Reproservice Gothenburg, Sweden 2012 Development of a Solvent Extraction Process for Group Actinide Recovery from Used Nuclear Fuel EMMA H. K. ANEHEIM Department of Chemical and Biological Engineering Chalmers University of Technology Abstract When uranium is used as fuel in nuclear reactors it both undergoes neutron induced fission as well as neutron capture. Through successive neutron capture and beta decay transuranic elements such as neptunium, plutonium, americium and curium are produced in substantial amounts. These radioactive elements are mostly long-lived and contribute to a large portion of the long term radiotoxicity of the used nuclear fuel. This radiotoxicity is what makes it necessary to isolate the used fuel for more than 100,000 years in a final repository in order to avoid harm to the biosphere. -
The Group 1A and Group 2A Elements
Cotton chapter 10,11 Group 1A Group 1A Qualitative alkali metal analysis Alkali Metals y The group 1A elements with their ns1 valence electron configurations are very active metals. They lose their valence electrons very readily. They have low ionization energies and react with nonmetals to form ionic solids. 2Na(s) +Cl2(g) Æ 2NaCl(s) y The expected trend in reducing ability, Cs>Rb>K>Na>Li y Alkali metals all react vigorously with water to release hydrogen gas. + ‐ 2M(s) +2H2O(l) Æ 2M (aq) +2OH(aq) +H2(g) y Observed reducing abilities: Li>K>Na First ionization energy Soda production Properties and Trends in Group 1A y The Group 1A metals exhibit regular trends for a number of properties. y Irregular trends suggest that factors are working against each other in determining a property (such as the density “discrepancy” between sodium and potassium). y The alkali metals have two notable physical properties: they are all soft and have low melting points. y When freshly cut, the alkali metals are bright and shiny—typical metallic properties. The metals quickly tarnish, however, as they react with oxygen in the air. Alkali Metal Oxides In the presence of ample oxygen, 4Li + O2 → 2Li2O(regularoxide) 2Na + O2 → Na2O2 (peroxide) K+O2 → KO2 (superoxide) Rb + O2 → RbO2 (superoxide) Cs + O2 → CsO2 (superoxide) The oxides of Group 1A Direct reaction of the alkali metals with O2 gives : Li ‐> oxide, peroxide (trace) Na ‐> peroxide , oxide (trace) K,Rb,Cs ‐> superoxide Diagonal Relationships: The Special Case of Lithium In some of its properties, lithium and its compounds resemble magnesium and its compounds.