polar bonds‚ nonpolar bonds‚ avogadro’s number‚ and calculating the atomic mass (unit?) * Chapter 4: Basically about theories of atoms and the atom itself 4-1: Theories The Greeks believed that all matter was composed of earth‚ fire‚ air and water. Democritus: the first person to propose the idea of atoms (that matter was not infinitely divisible): atomos. “Atoms are solid‚ homogenous‚ indestructible and indivisible.” Aristotle - DENIED IT. He is why Democritus’ atomic theory was rejected and
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MSE20-3: Introduction to Materials Science & Engineering Course Objective... Introduce fundamental concepts in Materials Science You will learn about: • material structure • how structure dictates properties • how processing can change structure This course will help you to: • use materials properly • realize new design opportunities with materials Chapter 1 - 1 COURSE MATERIALS (with WileyPLUS) Required text: • WileyPLUS for Materials Science and Engineering: An Introduction
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UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certificate of Education Ordinary Level CHEMISTRY Paper 1 Multiple Choice May/June 2005 1 hour Additional Materials: Multiple Choice Answer Sheet Soft clean eraser Soft pencil (type B or HB is recommended) 5070/01 w w w e tr .X m eP e ap .c rs om READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples‚ paper clips‚ highlighters‚ glue or correction fluid. Write your name‚ Centre number and candidate number on the answer
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includes information about some of the elements in Period 2. element symbol structure boiling point / °C carbon C macromolecular 4200 nitrogen N simple molecules N2 –196 fluorine F simple molecules F2 –188 neon Ne single atoms Ne –246 For Examiner’s Use (a) Why does neon exist as single atoms but fluorine exists as molecules? ........................................................................................................................................... ......................................
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Ionization Energy and Electron Affinity Ionization Energy is removing an electron Electron Affinity is adding an electron Ionization Energy • Energy required to remove an electron from a ground state atom Ionization Energy of Noble Gases • Noble gases have full orbitals‚ so it is difficult to remove an electron from them. But‚ it does become easier the further away the electrons get from the nucleus. Ionization Energy of Alkali Metals • Alkali Metals only have one valence electron
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formed between a metal and a non-metal‚ Covalent between two non-metals and Metallic between two metals. Ionic Bonding; Ionic bonds tend to form between metals whose atoms need to “loose” electrons to gain the nearest noble gas configuration and non-metals that need to gain electrons. These electrons are transferred from one atom to another. This gives one ion a positive charge and the other a negative one. The Opposite charges in the ion hold them together in a regular three dimensional lattice
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energy of a molecule reflects teh stability of the initial and final states. A lower BDE ensures stability and lowers the likelihood of hemolytic cleavage and eventual formation of a Grignard. Benzyllic radical R groups are the most stable due to electron delocalization in their resonance structure. Allylic radical R groups are also stable as their double bonds allow for similar resonance stabilization. Tertiary‚ Secondary‚ and Primary radicals follow in stability. They are followed by methyl radicals
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(RMSD): The root mean square deviation (RMSD) is a measure of structural differences that are observed on superimposition of two protein structures at a different time points i.e. current position and previous position. The RMSD values for backbone atoms of each residue were calculated for entire trajectory to see the evolution of structure with time. The RMSD plot is shown in Supplementary Figure S7 where timestep is plotted on X-axis while RMSD (Å) is plotted on Y-axis. The blue and red curve depicts
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COORDINATION COMPOUNDS: * FLEXIDENTATE CHARACTER OF POLYDENTATE LIGANDS; * Poly dentate ligands have flexi dentate character in the sense that all donors atoms may not form coordinate bonds with the central metal atom or ion. For example; EDTA which is the hexa dentate ligand also acts as tetra dentate or penta dentate in certain complexes. Similarly sulphate ion‚ which is a bi dentate ligand‚ also acts as a mono dentate ligand in certain complexes‚ e.g. in [Co(SO4)(NH3)5]Cl. * LABILE
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molecule Mass spectrometer converts sample into ions‚ and that these ions can be further fragmented (broken down) into smaller molecules. Ionisation can be achieved using various different techniques‚ electron ionisation‚ chemical ionisation and Fast atom bombardment. When sample is ionised the analyser portion of the mass spectrometer seperates the molecules based on their mass to charge ratio. A dector then detects the molecule weight of all the molecules present and a spectrum is obtained. Base
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