Name ______________________________ Date ____________
Due Date __________
Emission Line Spectrum
Purpose
A. To observe and identify metallic ions using flame tests.
B. Use a spectrometer to observe and draw the emission line spectra of gaseous elements.
Background
A. The flame test is used to visually determine the identity of an unknown metal or metalloid ion
based on the characteristic color the salt turns in a Bunsen burner flame. The heat of the flame
excites the electrons to a higher energy level. When the electrons fall back to their normal
levels, they emit visible light. The characteristic emission spectra can be used to differentiate
between some elements.
Limitations of the Flame Test
 The test cannot detect low concentrations of most ions.
 The brightness of the signal varies from one sample to another. For example, the yellow
emission from sodium is much brighter than the red emission from the same amount of
lithium.
 The test cannot differentiate between all elements. Several metals produce the same
flame color. Some compounds do not change the color of the flame at all.
B. The tubes contain a pure gas that is being excited with electricity. These give off a very precise
emission lines that can be observed with a spectrometer. Any electromagnetic radiation that is
outside the visible light spectrum (infrared and UV) cannot be observed.
Procedure:
A. Heat the paper clip/wire loop first in order to clean it.
Perform a flame test and record flame color with the naked eye.
B. Remove your goggles and use the spectrometer in order to see the spectral lines produced by
the different gases when excited.
Example of Data Collection
A. Simply record the solution and the resulting color when being heated by the Bunsen burner flame.
B. Correctly draw the spectral lines produced by each of the excited gases. See the example
below for the make-believe element Ryon (Ry). Be sure to put the colors in the correct areas.
Ry
red
orange
yellow
green
blue
indigo
700 nm
650nm
600 nm
550nm
500 nm
450 nm
violet
400 nm
“Conclusion” Paragraph
Write a conclusion for this lab that describes what was done. Use the following words in a
manner that shows your comprehension of them. Bohr model of the atom, electron, ground
state, stable, excited, light, quanta or quantum, photon, wavelength, color, emit, energy (flame
or electricity) and peanut butter.
Be sure to underline or highlight these words in your conclusion.