📚 Topic Summary
Mass spectrometry is a powerful analytical technique used to identify unknown compounds, determine the isotopic composition of elements, and elucidate the structure and chemical properties of molecules. In organic chemistry, it's invaluable for confirming the molecular weight of a synthesized compound and gaining insights into its fragmentation patterns, which can reveal structural information. Analyzing mass spectra involves identifying the molecular ion peak (M+), which corresponds to the molecular weight of the compound, and interpreting the various fragment ion peaks resulting from the molecule's breakdown. These fragments provide clues about the compound's structure, functional groups, and connectivity. Isotopes also play a crucial role, as their relative abundance can help confirm the identity of elements within the molecule.
This worksheet is designed to provide graduate organic chemistry students with a practical approach to understanding and interpreting mass spectrometry data. It covers key vocabulary, fill-in-the-blank exercises, and critical thinking questions to reinforce the core concepts and develop problem-solving skills.
🧪 Part A: Vocabulary
Match the following terms with their definitions:
| Term |
Definition |
| 1. Molecular Ion Peak |
A. The process where a molecule breaks apart in a mass spectrometer. |
| 2. Base Peak |
B. An atom with the same number of protons but a different number of neutrons. |
| 3. Fragmentation |
C. The ion formed by the removal of one electron from the parent molecule. |
| 4. Isotope |
D. The most abundant ion in the mass spectrum. |
| 5. m/z |
E. Mass-to-charge ratio. |
🧩 Part B: Fill in the Blanks
Complete the following paragraph using the words provided: mass, charge, molecular, fragments, spectrum.
In mass spectrometry, molecules are ionized and broken into __________. The __________ of these ions are then measured. The __________ ion peak corresponds to the __________ weight of the molecule. The resulting data is displayed as a __________, which plots the abundance of each ion against its mass-to-__________ ratio.
🤔 Part C: Critical Thinking
Explain how the fragmentation patterns observed in a mass spectrum can be used to determine the structure of an unknown organic compound. Provide an example of a common fragmentation pathway and the structural information it reveals.