1Ch 100: Fundamentals for ChemistryChapter 1: IntroductionLecture NotesWhat is Chemistry?• Chemistry is often described as the “central”science• Chemistry is the study of matter• Matter is the “stuff” that makes up the universe, i.e. anything that has mass and occupies space• The fundamental questions of Chemistry are:1. How can matter be described?2. How does one type of matter interact with other types of matter?3. How does matter transform into other forms of matter?2Major Developments in Chemistry I~400 BC: Democritus proposed the concept of the “atom”~300 BC: Aristotle developed 1stcomprehensive model of matter~700 AD: Chinese alchemists invent gunpowder1661: Robert Boyle proposed the concept of elements1770-90: Lavoisier proposed the concept of compounds & the Law of Mass Conservation1774: Priestly isolates oxygen1797: Proust proposed the Law of Definite Proportions1803: Dalton re-introduces the concept of the atom and establishes Dalton’s Laws1869: Mendeleev creates the 1stPeriodic Table1910: Rutherford proposes the “nuclear” model of the atom1915: Bohr proposes a “planetary” model of the hydrogen atom1920: Schroedinger publishes his wave equation for hydrogen1969: Murray Gell-Mann proposes the theory of QCD (proposing the existence of quarks)Major Developments in Chemistry IIDiscovery of subatomic particles:1886: Proton (first observed by Eugene Goldstein)1897: Electron (JJ Thompson)1920: Proton (named by Ernest Rutherford)1932: Neutron (James Chadwick)Other Important Discoveries:1896: Antoine Henri Becquerel discovers radioactivity1911: H. Kamerlingh Onnes discovers superconductivity in low temperature mercury1947: William Shockley and colleagues invent the first transistor1996: Cornell, Wieman, and Ketterle observe the 5th state of matter (the Bose-Einstein condensate) in the laboratory3Scientific Method1. (OBSERVATION) Recognize a problem– Make observation – Formulate a question2. (EXPLANATION) Make an educated guess -a hypothesis– Predict the consequences of the hypothesis3. (VALIDATION) Perform experiments to test the predictions– Does experimental data support or dispute hypothesis?4. Formulate the simplest rule that organizes the 3 main ingredients - develop a theory4Provides aBasis forFurther ExperimentationTentative ExplanationofCertain FactsHypothesisConsiderable Evidenceor FactsSupport ItExplanation of theGeneral Principlesof Certain PhenomenaTheoryEXPLANATIONSSimple Statementof Natural PhenomenaNo ExceptionsUnder the GivenConditionsLaw5Bottom Line: The Scientific Attitude• All hypotheses must be testable (i.e. there must be a way to prove them wrong!!)• Scientific: “Matter is made up of tiny particles called atoms”• Non-Scientific: “There are tiny particles of matter in the universe that will never be detected”The Particulate Nature of Matter• Matter is the tangible substance of nature, anything with mass that occupies space• At the most fundamental level, matter is discrete or particulate in nature• The smallest, most basic units of matter are called atoms• All matter is thus comprised of individual atoms, or specific combinations of atoms called molecules• Molecules can be broken apart into their constituent atoms but atoms cannot be further broken apart and still retain the properties of matter • Matter can exist in one or more physical states (or phases)6States of MatterSolid → Liquid → Gas+Energy +EnergySolid ← Liquid ← Gas+Energy+EnergyState Shape Volume Compress FlowSolid Keeps ShapeKeeps VolumeNo NoLiquid Takes Shape of ContainerKeeps VolumeNo YesGas Takes Shape of ContainerTakes Volume of ContainerYes YesClassification of MatterMatter can be classified as either Pure or Impure:– Pure• Element: composed of only one type of atom– Composed of either individual atoms or molecules (e.g. O2)• Compound: composed of more than one type of atom – Consists of molecules– Impure (or mixture)• Homogeneous: uniform throughout, appears to be one thing– Pure substances– Solutions (single phase homogeneous mixtures)– Suspensions (multi-phase homogeneous mixtures)• Heterogeneous: non-uniform, contains regions with different properties than other regionsPure SubstanceConstant CompositionHomogeneousMixtureVariable CompositionMatter7Separation of Matter• A pure substance cannot be broken down into its component substances by physical means only by a chemical process– The breakdown of a pure substance results in formation of new substances (i.e. chemical change)– For a pure substance there is nothing to separate (its only 1 substance to begin with)• Mixtures can be separated by physical means (and also by chemical methods, as well)• There are 2 general methods of separation1. Physical: separation based on physical properties1. Filtration2. Distillation3. Centrifugation2. Chemical: separation based on chemical
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