spectroscopy

what does mass spectrometry tell us?

• relative atomic mass of an element or relative formula mass of a compound

what does m/z mean?

• mass/charge

what is the likely charge of an element in mass spectroscopy in alevel?

• +1

what are the 3 types of spectroscopy?

• mass spectroscopy

• infrared spectroscopy

• nuclear magnetic (NMR) spectroscopy

what does infrared spectroscopy tell us?

• identifies functional groups

what does nuclear magnetic (NMR) spectroscopy tell us?

• determines molecular structure

what are the common fragment ions?

• CH₃⁺ 15

• C₂H₅⁺ 29

• C₃H₇⁺ 43

• OH⁺ 17

• C₄H₉⁺ 57

what is the unit of wavelengths for this topic?

• cm^-1

• as it’s the number of waves found in 1cm

what does infrared spectrometer measure?

• how much infrared radiation passes through a sample

what happens if the bond absorbs some infrared radiation at a particular wavenumber?

• transmittance drops and forms a trough

how is the fingerprint region useful?

• possible to identify an unknown substance by comparing its fingerprint region with the fingerprint regions of known substances

other than troughs what else may an infrared spectrum contain?

• background ‘noise’

where is the fingerprint region?

• anything below 1500cm^-1 on the graph

what are uses for infrared spectroscopy?

• breathalysers to detect ethanol

• gas detectors to analyse air pollution as can detect carbon dioxide, carbon monoxide and hydrocarbon molecules