Atomic Absorption and Emission Flame Tests Picture from

Atomic Absorption and Emission

Flame Tests Picture from: http: //aarcaro. wordpress. com/1 0 th/mathenvirochem/flame-testlab/ What causes the colour of the metal ions in the flame test?

Photon of light released when electron returns to lower energy level Electron is excited to higher energy level

Limitations of Flame Test n n n 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.

Emission Spectrum of Hydrogen Animation of spectral lines for H Picture from: http: //www. 800 mainstreet. com/spect/emission-flame-exp. html

Balmer Series for Hydrogen Adapted from: http: //www. avogadro. co. uk/light/bohr/spectra. htm Ground state Excite Balmer Series

Atomic Absorption Spectroscopy (AAS) n n http: //www. youtube. com/watch? v=HBeg. TB_WDx. Q http: //www. youtube. com/watch? v=Wkcio. QGf. Ag. U&feature=player_embedde d

* * Photons of specific wavelenghts Sample compound chopped into pulses atomises Hollow Cathode Lamp Hg * Specific wavelengths are not absorbed if atom is not Hg – move to monochromator and detector 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 Hg X Z Hg Sample injected More detailed animations http: //www. umd. umich. edu/casl/natsci/slconline/ADVAA/Adv. AA. swf http: //www. shsu. edu/~chm_tgc/sounds/sound. html - flash video with sound