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7 Cards in this Set
- Front
- Back
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Fingerprint region |
The area right of 1500cm-1 |
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What causes IR peaks |
If a molecule has a dipole moment, it can absorb infrared radiation. Strong polar bonds absorb strongly causing deep peaks. |
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How do non-polar molecules absorb light? |
All bonds vibrate and can stretch, bend or vibrate. When they stretch, it causes an uneven charge distribution allowing it to absorb IR radiation. |
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Which absorbs at higher wavelength numbers single bonds or double bonds? |
Double bonds because they need more energy. |
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What 3 ways do you describe an IR peak? |
Location (wave number), intensity (relative % absorbed, strong medium or weak) and shape (broad, narrow, sharp etc) |
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What is the systematic process of identifying a compound? |
1. Locate 3000cm-¹. Look to the right of this value. If there are strong peaks, an alkyl group is present.
2. Look to the left of 3000cm-¹. If there are weak narrow peaks this may suggest an alkene.
3. Look at around 3300cm-¹ for a strong parabolic peak (O-H bond) or a medium weak triangular peak (N-H) or a very broad strong O-H peak from COOH. 4. A strong finger-like peak between 1650 and 1800cm-¹ is due to C=O. A medium sharp peak between 1500 and 1680cm-¹ is probably C=C |
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Why do they use C13 not C12? |
Because only nuclei with an odd mass number have nuclei spin. |
