1. Atomic Absorption and Emission

2. What causes the colour of the metal ions in the flame test?
Flame Tests
Picture from:
What causes the colour of the metal ions in the flame test?

3. Electron is excited to higher energy level
Photon of light released when electron returns to lower energy level
Photon of light released when electron returns to lower energy level
Electron is excited to higher energy level
Hydrogen. n3-2 and n4-2 within visible range – less energy to drop n3-n2, red light

4. Limitations of Flame Test
Not sensitive
Qualitative only
Can only be used for a small number of metal ions
Contamination of salts will result in inaccurate analysis as the flame colour will alter
There can be difficulty distinguishing the flame colour.

5. Emission Spectrum of Hydrogen
Animation of spectral lines for H
Picture from:

6. Balmer Series for Hydrogen
Adapted from:
Ground state
Excite
Balmer Series

7. Atomic Absorption Spectroscopy (AAS)

8. * Photons of specific wavelenghts chopped into pulses
Sample compound atomises
Hollow Cathode Lamp * Hg
Specific wavelengths are not absorbed if atom is not Hg – move to monochromator and detector Hg Hg * *
Excited Hg atoms release photons (*) of specific wavelengths when electrons return to ground state
Hg atoms absorb specific wavelengths of light – causes electrons to excite – light not transmitted to monochromator or detector Y X Hg Hg Z
Sample injected
More detailed animations
- flash video with sound