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Concept Development Studies in Chemistry (Hutchinson)

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    This collection is presented to redirect the focus of learning. In each concept development study, a major chemical concept is developed and refined by analysis of experimental observations and careful reasoning. Each study begins with the definition of an initial Foundation of assumed knowledge, followed by a statement of questions which arise from the Foundation. Analysis of these questions is presented as a series of observations and logical deductions, followed by further questions. This detailed process is followed until the conceptual development of a model provides a reasonable answer to the stated questions.

    • 1: Preface to Concept Development Studies in Chemistry
      This is the preface to the Concept Development Studies in Chemistry, a series of modules for introducing chemical concepts in a General Chemistry course.
    • 2: The Atomic Molecular Theory
      A development of the atomic molecular theory from the law of multiple proportions and law of definite proportions
    • 3: Relative Atomic Masses and Empirical Formulae
      We begin by assuming the central postulates of the Atomic Molecular Theory. These are: the elements are comprised of identical atoms; all atoms of a single element have the same characteristic mass; the number and masses of these atoms do not change during a chemical transformation; compounds consist of identical molecules formed of atoms combined in simple whole number ratios. We also assume a knowledge of the observed natural laws on which this theory is based.
    • 4: The Structure of an Atom
      We assume that most of the common elements have been identified, and that each element is characterized as consisting of identical, indestructible atoms. We also assume that the atomic weights of the elements are all known, and that, as a consequence, it is possible via mass composition measurements to determine the molecular formula for any compound of interest.
    • 5: Quantum Energy Levels in Atoms
      he atomic molecular theory provides us a particulate understanding of matter. Each element is characterized as consisting of identical, indestructible atoms with atomic weights which have been determined. Compounds consists of identical molecules, each made up from a specific number of atoms of each of the component elements. We also know that atoms have a nuclear structure, meaning that all of the positive charge and virtually all of the mass of the atom are concentrated in a nucleus.
    • 6: Covalent Bonding and Electron Pair Sharing
      That is, we assume the Periodic Law that the chemical and physical properties of the elements are periodic functions of atomic number. We further assume the structure of the atom as a massive, positively charged nucleus, whose size is much smaller than that of the atom as a whole, surrounded by a vast open space in which move negatively charged electrons.
    • 7: Molecular Geometry and Electron Domain Theory
      We begin by assuming a Lewis structure model for chemical bonding based on valence shell electron pair sharing and the octet rule. We thus assume the nuclear structure of the atom, and we further assume the existence of a valence shell of electrons in each atom which dominates the chemical behavior of that atom. A covalent chemical bond is formed when the two bonded atoms share a pair of valence shell electrons between them.
    • 8: Molecular Structure and Physical Properties
      Atoms have a nuclear structure, meaning that all of the positive charge and virtually all of the mass of the atom are concentrated in a nucleus which is a very small fraction of the volume of the atom. The properties of atoms can be understood by a model in which the electrons in the atom are arranged in "shells" about the nucleus, with each shell farther from the nucleus than the previous. The electrons in outer shells are more weakly attached to the atom than the electrons in the inner shells.
    • 9: Chemical Bonding and Molecular Energy Levels
      A development of the quantum mechanical concepts of bonding using valence bond and molecular orbital descriptions to account for bond strength and molecular ionization energies.
    • 10: Energetics of Chemical Reactions
      The heat released or consumed in a chemical reaction is typically amongst the most easily observed and most readily appreciated consequences of the reaction. Many chemical reactions are performed routinely specifically for the purpose of utilizing the heat released by the reaction.
    • 11: The Ideal Gas Law
      Our ultimate goal is to relate the properties of the atoms and molecules to the properties of the materials which they comprise.
    • 12: The Kinetic Molecular Theory
      Our continuing goal is to relate the properties of the atoms and molecules to the properties of the materials which they comprise.
    • 13: Phase Equilibrium and Intermolecular Interactions
      The "phase" of a substance is the particular physical state it is in. The most common phases are solid, liquid, and gas, each easily distinguishable by their significantly different physical properties. A given substance can exist in different phases under different conditions: water can exist as solid ice, liquid, or steam, but water molecules are the same regardless of the phase.
    • 14: Reaction Equilibrium in the Gas Phase
      In beginning our study of the reactions of gases, we will assume a knowledge of the physical properties of gases as described by the Ideal Gas Law and an understanding of these properties as given by the postulates and conclusions of the Kinetic Molecular Theory. We assume that we have developed a dynamic model of phase equilibrium in terms of competing rates. We will also assume an understanding of the bonding, structure, and properties of individual molecules.
    • 15: Acid-Base Equilibrium
      An acid is a substance whose molecules donate positive hydrogen ions (protons) to other molecules or ions. When dissolved in pure water, acid molecules will transfer a hydrogen ion to a water molecule or to a cluster of several water molecules. A base is a substance whose molecules accept hydrogen ions from other molecules.
    • 16: Reaction Rates
      we seek an understanding of the rates of chemical reactions. We will define and measure reaction rates and develop a quantitative analysis of the dependence of the reaction rates on the conditions of the reaction, including concentration of reactants and temperature. This quantitative analysis will provide us insight into the process of a chemical reaction and thus lead us to develop a model to provide an understanding of the significance of reactant concentration and temperature.
    • 17: Equilibrium and the Second Law of Thermodynamics
      When a mixture of reactants and products is not at equilibrium, the reaction will occur spontaneously in one direction or the other until the reaction achieves equilibrium. What determines the direction of spontaneity? What is the driving force towards equilibrium? How does the system know that equilibrium has been achieved? Our goal will be to understand the driving forces behind spontaneous processes and the determination of the equilibrium point.

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