When the nuclei of some atoms behave as if they are tiny magnets
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What is nmr?
Nuclear magnetic resonance
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Explain nmr
Placing nuclei in a strong magnetic field. If they align with the field, they have lower energy than those against it. A pulse of (RF) radiation promotes lower energy to higher energy (resonance). They then lose the energy which can be detected
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What's the most commonly investigated nucleus? What's it called? What does it provide information on?
The hydrogen atom. H-n.m.r or proton n.m.r. Information on the chemical environment in which hydrogen nuclei are found.
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What are common to all H-n.m.r spectra?
Absorption on y-axis. Chemical shift on x-axis. Chemical shift goes from 0 ppm (right hand side) to around 10 ppm.
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What is the compound that usually causes an absorption at 0ppm?
tetramethylsilane (TMS)
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Why does High-resolution H-n.m.r have more peaks than low-resolution?
Each H nucleus behaves as a tiny magnet and it can be one of 2 orientations, depending on it being in the low or high energy level. Each causes a slightly different local magnetic field so the absorption peaks are split
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What does the amount of splitting indicate?
The number of hydrogen atoms attached to the carbon atom next to the the one you are looking at
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