52 Chemical Bonding and Molecular Structure 53 I. Structure of Matter (20%) B. Chemical bonding 1. Binding forces a. Types: ionic‚ covalent‚ metallic‚ hydrogen bonding‚ van der Waals (including London dispersion forces) c. Polarity of bonds‚ electronegativities 2. Molecular models a. Lewis structures TYPES OF CHEMICAL BONDING Ionic Bonding - two atoms of opposite charge electrically attracted to one another Covalent Bonding - two atoms each sharing electrons within a molecular orbital Metallic
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“A brief history of chemical warfare” By Harold Maass For more than 2‚000 years. As early as 600 B.C.‚ the Athenians poisoned the wells of the Spartans‚ who later tried lobbing burning sulfur pitch over the walls of Athens‚ hoping to fill the city with toxic smoke. Genghis Khan used that same trick‚ catapulting burning sulfur pitch during his siege of fortified cities around A.D. 1200. Over the centuries‚ various armies put poisons on arrows and in bullets to make them more lethal. But it wasn’t
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whilst the Rf value for benzil was 2.3 cm ÷ 4.5 cm= 0.51. From these results‚ one can see that benzil has a higher Rf than benzoin. This is because benzil is a less polar compound compared to benzoin. To explain further‚ with TLC and polarity‚ Rf values and polarity are inversely related. The spot with the highest Rf value is the least polar (fastest moving)‚ and the spot with the lowest Rf value is the most polar (slowest moving). So because of the benzil travelling further when divided by the distance
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Titanium Titanium is a transition metal that was discovered in the year 1791 by an English pastor named William Gregor. The discovery was made when Gregor was by a Stream in the parish of Mannacan in Cornwall‚ England and found black magnetic sand. When Gregor analyzed this sand‚ he found out it was made up of the oxides of iron and an undefined and yet undiscovered metal.
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FORMAL LAB REPORT INTRODUCTION John Dalton’s atomic theory states that elements combine in simple numerical ratios to form compounds. A compound‚ no matter how it is formed‚ always contains the same elements in the same proportion by weight. The law of mass conservation states that mass can neither be created nor destroyed. In this experiment‚ the mass of the metal was not destroyed or created; the metal’s mass was simply changed into a compound form once the gas
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Thomas Newberg Chemical Weapons Convention Historically chemical weapons are rarely seen in combat but when they are they are used to great effect‚ killing thousands and injuring many more. Chemical weapons were first used in combat in May 1915 when the Germans released chlorine gas against the French in the Battle of Ypres. Over the course of WWI new chemical agents were developed including cyanide‚ phosgene and mustard gas. The Geneva Protocol of 1925 condemned chemical weapons but states that
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The polarity of water Polarity means that the molecule has both a positively and negatively charged end. More important‚ the polarity of water is responsible for effectively dissolving other polar molecules‚ such as sugars and ionic compounds such as salt. Ionic compounds dissolve in water to form ions. This is important to remember because for most biological reactions to occur‚ the reactants must be dissolved in water. Because water is able to dissolve so many common substances‚ it is known as
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CHEMICAL ATTACK ON SYRIA Over 110‚000 people have died in Syria since the beginning of a years-long conflict in the country. On August the 21st‚ the U.S government says that 1‚429 died through the chemical attacks which marked the sea change in foreign policy towards the Middle Eastern country. The impact of poison gas is horrific and fatal. Those exposed to the nerve agent can die within 15 minutes of exposure. Mr. Obama’s absolutist position against it is backed up by international law and the
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Chemical reactions * Chemical reactions occur when substances undergo chemical changes to form new substances * Production of gas and change of color are sings of chemical reactions * Chemical reactions rearrange atoms * A reactant is a substance or molecule that participates in a chemical reaction * A product is a substance that forms in a chemical reaction Energy and Reactions * Energy must be added to break bonds. * Many forms of energy can be used to break bonds:
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Observations of Chemical Changes Page. 14 Objectives: The objectives of this experiment are: 1. To observe some properties of chemical reactions 2. to associate chemical properties with household products Background Information: Chemical changes are often accompanied by physical changes. Three that you should not see in this lab are changes in temperature‚ presence of a flame‚ and evolution of light‚ as when as firefly glows. Three physical changes that indicate a chemical change may have
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