| Date | May 2014 | Marks available | 4 | Reference code | 14M.3.sl.TZ2.1 |
| Level | SL | Paper | 3 | Time zone | TZ2 |
| Command term | Distinguish | Question number | 1 | Adapted from | N/A |
Question
Modern analytical techniques are used widely for different purposes in everyday life.
Two types of spectroscopy are absorption and emission. Distinguish between each type of spectra, including how each is produced.
Absorption spectra:
Emission spectra:
Markscheme
Absorption spectra:
(when radiation is passed through sample) atom/ion/molecule becomes excited / electrons raised to higher energy level/state / OWTTE;
only specific frequencies/wavelengths absorbed / black lines on a coloured background / spectrum shows where absorption happens, such as dips (in the IR spectrum) / OWTTE;
Emission spectra:
(energy given out by) excited atom/ion/molecule moves to lower energy state / excited electrons move to lower energy level/ground state / OWTTE;
colours same as those missing from absorption spectra / coloured lines on black background / only specific frequencies/wavelengths emitted / OWTTE;
Difference may also be shown by two different representations of spectra.
Examiners report
Answers generally showed understanding of the relationship between the spectra and electronic transitions. Some candidates failed to highlight that emission spectra are obtained from an excited sample.
