Introduction to the Lanthanides 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; r understand how the size of the lanthanide ions affects certain properties and how this can 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
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1.1 The atoms‚ during bond formation‚ may lose or gain electrons (valence electrons) in order to achieve a stable state‚ or technically speaking‚ a stable electron configuration. Usually metal atoms lose electrons and non-metals gain electrons in order to achieve electron stability. When dealing with bond formation (Ionic bonding for example) we need to analyse the outer shell of the atom. Metals usually present 1‚ 2 or 3 electrons in their outer shell therefore they have to give them away to achieve
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Introduction: • All organic compounds can be derived into two broad classes 1. Aliphatic compounds Nonaromatic hydrocarbons such as alkanes‚ alkenes or alkynes 2. Aromatic compounds A series of cyclic unsaturated compounds with unusually high stability • The properties and reactions of aromatic compounds are exemplified / demonstrated by the properties and reactions of benzene (the “parent” aromatic molecule) • Benzene Structure: MF: C6H6 DBE = • Properties and Reactions of Benzene 1
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Atom Bonding Lab Introduction: Atoms bond in covalent bonds and ionic bonds. A covalent bond is when atoms share electrons in order to gain stability with each other (Larsen). To have stability which each other‚ the atoms share electrons so that their outer electron shell is equal. Ionic bonding is the complete transfer of valence electron(s) between atoms. It is a type of chemical bond that generates two oppositely charged ions (Larsen‚ 2010). Element that have a positive ion are able to bond
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configuration are due to (a) very little engery difference between (n–1) d and ns orbitals and (b) extra stability of half filled and completely filled orbitals in case of Cr and Cu in 3d series. Cr : Is 2 2s2 2p6‚ 3s2 3p6 4s1 3d5 Cu : Is2 2s2 2p6‚ 3s2 3p6 4s1 3d10 To write the electronic configuration of Mn+‚ the electrons are first removed from ns orbital and then from (n - 1) d orbitals of neutral‚ atom (if required). For example‚ the electronic configuration of Cu+‚ Cu2+ and Cr3+ are respectively 3d10
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Acta mater. 48 (2000) 4709–4714 www.elsevier.com/locate/actamat GADOLINIA-DOPED CERIA AND YTTRIA STABILIZED ZIRCONIA INTERFACES: REGARDING THEIR APPLICATION FOR SOFC TECHNOLOGY A. TSOGA1*‚ A. GUPTA1‚ A. NAOUMIDIS1 and P. NIKOLOPOULOS2 Institut fur Werkstoffe und Verfahren der Energietechnik (IWV1)‚ Forschungszentrum Julich‚ D-52425 ¨ ¨ Julich‚ Germany and 2Chemical Engineering Department‚ University of Patras‚ GR 265 00 Patras‚ Greece ¨ 1 Abstract—For solid oxide fuel cells (SOFCs) operating
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Law | | | | | | | | 4‚5 | 3.1 The Applications of Hess’s Law | | | | | | 4.0 Standard Molar Enthalpy Change of Formation‚ ΔHof | | | | 6‚7 | 4.1 The Stability of A Compound | | | | | | | 4.2 Using ΔHof Values To Predict The Relative Stability Of A Compound | | | 5.0 Standard Molar Enthalpy Change of Combustion‚ ΔHoc | | | 8‚9 5.1 Standard Enthalpy Change of Combustion and Molecular Structure | | |
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displacement of shared electron pair in a carbon chain towards more electronegative atom or group. Types of Inductive effect : 1.Negative Inductive Effect : (—I effect‚ Electron withdrawing effect) when an electronegative atom or group (more electro negative than hydrogen)is attached to the terminal of the carbon chain in a compound‚ the electrons are displaced in the direction of the attached atom or group. -NO2 > -CN > -COOH > F > Cl > Br > I > OH > C6H5 >H 2. Positive Inductive
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covalent. In bonding the goal of the atoms involved is to reach a level of stability with less energy. In order to reach the epitome of stability‚ as in the case of noble gases‚ an atom strives to complete its outer shell. Either losing or gaining electrons may do this‚ which concludes in an ionic bond or the sharing of electrons with other atoms which makes a covalent bond. Ionic bonds‚ as you can probably surmise form from ions. Ions are made when an atom gains an electron to form a negative ion
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EAS 199A Lecture Notes: Basic Electricity Fall 2011 This course module introduces the basic physical models by which we explain the flow of electricity. The Bohr model of an atom – a nucleus surrounded by shells of electrons traveling in discrete orbits – is presented. Electrical current is described as a flow of electrons. Ohm’s law – the relationship between voltage‚ current and electrical resistance – is introduced. Learning Objectives Understanding the basic principles of electricity is
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