Expt10_lewis - Experiment 10 Molecular Geometry and...

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97 Experiment 10 Molecular Geometry and Molecular Models molecular geomometry background.wpd INTENT The purpose of this experiment is to introduce to you some of the basic theories and techniques used by chemists to predict the electronic structure and geometries of molecules and complex ions. These include Lewis structures and Valence Shell Electron Pair Repulsion (VSEPR) Theories, as well as the concepts of hybridization, isomerism, and resonance. INTRODUCTION You have been studying the rules which help us to predict whether combinations of atoms produce ionic or covalent substances and what the formulas of those substances might be. Equally important to the chemical and physical properties of many substances is the arrangement of their atoms in space (their geometries). Biology courses have taught you that the shapes of DNA, proteins and other biological molecules determine their biological behavior. Earlier in CHM1025, you saw that a variation in the arrangement of carbon atoms produces the great difference in properties of transparent, colorless diamond and opaque, black graphite. Similarly, the arrangement of atoms in a simple molecule like carbon dioxide can determine its molecular polarity, and by this, its melting temperature (mp), boiling temperature (bp), heat of fusion, heat of vaporization, and solubility characteristics. DISCUSSION To start, you will be asked to draw Lewis diagrams for specific molecules and certain ions that contain covalent bonds. As you go through these exercises, some new concepts will be introduced. You will have to consider the existence of isomers and resonance forms in some of the examples. You will then predict the geometry of the ions and molecules in terms of V alence S hell E lectron P air R epulsion (VSEPR) theory (see Class Handout) and to describe the orbitals used for bonding by the central atom using atomic orbital hybridization theory (CHM2045 topic). You will also actually assemble 3-D models of all of the examples and from these draw conventional 2-D pictures of the 3-D structures.
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Expt 10 Formulas Number 21 through 25 will be assigned on Wednesday 21 st June at the end of Laboratory. 21) ? 22) ? 23) ? 24) ? 25) ? Remember: Lewis Diagram, Isomers and Resonance Forms VSEPR Notation, Molecular Polarity, and Geometric Shape.
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Expt10_lewis - Experiment 10 Molecular Geometry and...

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