the periodic table was occupied by multiple entities. Hence Todd made the suggestion‚ which Soddy adopted‚ that a suitable name for such an entity would be the Greek term for "at the same place". Soddy’s own studies were of radioactive (unstable) atoms. The first observation of different stable isotopes for an element was by J. J. Thomson in 1913. As part of his exploration into the composition of canal rays‚ Thomson channeled streams of neon ions through a magnetic and an electric field and measured
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nature. A. oxygen atoms are electron seeking (electronegative)‚ especially compared to hydrogen; thus for an oxygen-hydrogen bond: B. The polar character of water allows water molecules to form many (up to 4) hydrogen bonds. II. What properties of water are important for life? A. Cohesion of water molecules 1. Cohesion: e.g.: 2. Adhesion: e.g.: 3. Surface tension: B. Ability to moderate temperature 1. The unusual specific heat of water leads to temperature stability specific heat –
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calculations carried out in gas phase at temperature 293.15 k and pressure 1 atm. The simulation results revealed that the trans configuration of azocubane exhibits more stability‚ low reactivity and more detonation property as compared to the cis trans configuration of azocubane. Keywords: Azocubane‚ Cis and trans configurations‚ DFT study‚ Stability‚ Reactivity. Introduction Cubane‚ first appeared on the scientific research stage after painstaking experimentation and was conclusively synthesized by Eaton
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chain‚ position and optical isomerism. Heptane has 9 isomer‚ Octane 18 and Decane 75. Nomenclature: 164 Preparation:- Wurtz reaction:- Follow mainly free radical mechanism Useful in preparing an alkane containing even number of carbon atoms Stepping up reaction Frankland reaction From Grignard reagent (RMgX) From unsaturated hydrocarbons:- Sabatier-Senderens reduction 4. From carboxylic acids- Decarboxylation.- Kolbe’s electrolytic method- Physical Properties:- (1) Nature:-
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ionizes 100%. The stronger an acid is‚ the more easily it loses a proton‚ H+. Two key factors that contribute to the ease of deprotonation are the polarity of the H—A bond and the size of atom A‚ which determines the strength of the H—A bond. Acid strengths are also often discussed in terms of the stability of the conjugate base. Sulfonic acids‚ which are organic oxyacids‚ are a class of strong acids. A common example is toluenesulfonic acid (tosylic acid). Unlike sulfuric acid itself‚ sulfonic
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produced is then analyzed using melting point and 1H NMR spectroscopy. Theory The Wittig reaction prepares alkenes from carbonyl compounds by attacking a phosphorus ylide with a nucleophilic carbon atom stabilized by a triphenylphosphonium group. An ylide is a compound that contains two oppositely charged atoms bonded together with complete octets and is generated through phosphonium salts. This experiment is a modified Wittig reaction that uses a Horner-Emmons-Wittig reagent that is more acidic than
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Gr7 Science: Applications of the Atom Can The Demonstrated Vast Destructive Power of Nuclear Bombs Continue To Act As A Deterrent To World War III? In early August 1945 an American B-‐29 bomber‚ along with two other planes‚ dropped Little Boy onto the Japanese City of Hiroshima. Then
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each motion is accompanied by a wave. The strength of the total particle wave at each point corresponds to the probability that the particle may be found there. Applying this principle we can explain all kinds of phenomena‚ from the properties of atoms and radioactivity to light reflection. 2. Electron Double Slit Experiment a. Electrons are fired (possibly one at a time) toward a screen with two slits and each electron that passes through leaves a dot on a film plate. The dots accumulate on
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biological target. Modern drug discovery involves the identification of screening hits‚ medicinal chemistry and optimization of those hits to increase the affinity‚ selectivity (to reduce the potential of side effects)‚ efficacy/potency‚ metabolic stability (to increase the half-life)‚ and oral bioavailability. Once a compound that fulfils all of these requirements has been identified‚ it will begin the process of drug development prior to clinical trials. One or more of these steps may‚ but not necessarily
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of atoms. A lot of property changes during a chemical reaction too. Chemical reactions are also very hard to reverse. One example of chemical change is when sugar is combined with sulfuric acid. We can tell it is a chemical change because heat and bubbles are produced‚ and carbon was separated from the other substances. On the other hand‚ physical reaction only does macroscopic changes to the matter‚ for example‚ altering the shape‚ and painting the matter. There is not rearrangement of atoms in
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