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Chemistry LibreTexts

Flame Colors

  • Page ID
    2998
  • [ "article:topic", "Fundamental" ]

    Chemical Concepts Demonstrated

    • Atomic emission spectra
    • Bohr atomic model

    Demonstration

    Different types of powdered metals and salts are sprinkled over a flame. flame (1).gif

    Observations

    The video shows the metals and salts in this order:

    Metal or salt:

    1. Copper acetate

    2. Copper

    3. Potassium iodide

    4. Magnesium

    5. Iron

    6. Lithium carbonate

    7. Strontium nitrate

    8. Sodium chloride

    Observations:

    Green flame

    Blue-green flame

    Violet flame

    White sparks

    Yellow sparks

    Blue flame

    Red flame

    Yellow flame

    Explanation

    When a metal or metal salt is added to a flame, a combustion reaction ensues.  This reaction excites an electron in the metal from its ground state to a higher orbital.  In order to return to its ground state, the electron releases the additional energy in the form of light. 

    Different metal electrons emit different wavelengths of light to return to their respective ground states, so the flame colors are varied.  These flames can be used to produce atomic emmision spectra of the elements combusted.   Using known values of emmision spectra, one can perform a flame test on un unknown substance, gather an emmision spectrum from it, and determine which elements are in the unknown substance.

    For example, in the case of copper ion, there are multiple different "paths" that the excited electrons can follow to emit photon of certain discrete energy. This produces multiple spectra lines because each discrete energy level difference will yield a specific wavelength of light, which determines the color. 

     

    CuSO4.png     Cu configuration.png

    Figure 1 (left): Copper is heated and as the electrons fall back, certain color of light is emitted. (right): Submicroscopic view of the electron movement, as electrons fall