CHEM 2535 Lecture Notes - Lecture 13: Atomic Mass, Molecular Mass, Single-Photon Emission Computed Tomography
Document Summary
Mass spec: nominal mass is the mass to the nearest integer, base peak is the tallest peak. Atomic mass of an atom = (exact mass of isotope 1)*(abundance of isotope 1) + (exact mass of isotope 2)*(abundance of isotope 2) Molecular weight= addition of all atomic mass values. Exact mass of compounds = addition of exact mass of each atom. Nominal mass= exact mass of lightest isotope rounded to nearest whole interger. Esi: only a few peaks, molecular ion is usually the tallest peak, tells you exact mass of a compound. Rules of thumb: m+2 ~33% as tall as m = cl, m+2 ~100% as tall as m = br, m+2 ~4% as tall as m = s. Uv-vis spectroscopy: deals with electronic states, observe energy level of orbitals. Ir spectroscopy: used to characterize compounds, allows us to know which functional groups are present, uses lower energy radiation it deals with lower energy vibrational states.
