CHEM 140B Chapter 10: Textbook Notes
1 Feb 2017
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Using nuclear magnetic resonance spectroscopy to deduce structure. Nmr spectroscopy: can identify structure of organic molecule, mri: imaging of whole body organs. Can distinguish compounds based on physical properties (boiling point, melting point) With larger molecules, harder to distinguish the correct structure though reactivity or physical properties; many structures can be possible. Spectroscopy: technique used for analyzing structure of molecules depending on how they absorb electromagnetic radiation, nuclear magnetic resonance (nmr) spectroscopy. Determines structure based on vicinity of individual nuclei (of h and c) Infrared (ir) spectroscopy: ultraviolet (uv) spectroscopy, mass spectrometry (ms) Molecules undergo distinctive excitations: emr has different wavelengths/ frequencies. Wavelength x frequency = speed of light: molecules absorb emr in quanta, or discrete packets of energy. Absorption only occurs when emr supplies the exact amount of energy needed to allow molecules to move from ground state to excited state. X-rays need over 300 kcal/mol of energy to cause electronic transition. Move electrons from inner to outer shells.
