Dr. May - Chemistry Laboratory
Flame Tests for Identifying Elements
Introduction:
Have you ever wondered what gives fireworks their color? The light you see is the
visible electromagnetic energy released when electrons (which have been forced out to
higher energy orbitals by heat) fall back to their assigned orbitals. The atoms become
excited when they are heated and certain electrons move to higher energy levels. Atoms do
not stay excited very long and the electrons soon move back to their normal energy levels.
The extra energy is released as photons of electromagnetic energy. If this energy is in the
visible region of the spectrum, we see it as colored light.
Each element has its own unique electron arrangement, which determines the color.
We can identify some elements by the color we see when we heat the salts of the elements
in a clean, hot flame.
In this experiment, you will observe the colors of several compounds and determine
the color of specific elements. This is an example of Qualitative Analysis, which
describes a property without measuring it.
Materials:
 Bunsen burner, one at each station
 Ni-Chrome wire with a handle, one at each station
 Eleven known compounds, see data sheet
Procedure:
At each station you will collect a small amount of sample on the loop of the wire,
place the sample in the flame, record the color, and make any other observations. The
color choices are Yellow, Scarlet (red), Emerald (green), Carmine (red), Azure (blue),
and Violet (may look milky yellow).
Please keep samples and wire at the correct station to prevent cross-contamination
of samples. When you have made your observations at one station move on and allow the
next team to move in.
1
If an atom of strontium is exposed to a flame, the atom absorbs some of the light
energy. In this excited state, electrons will move from one energy level to a higher level as
shown between A and B below. Because excited atoms soon lose the energy they have
gained, electrons will drop back to a lower energy level. The diagram below shows an
electron of a strontium atom subjected a flame. After absorbing the energy the electron
moves from A to a higher level such as B. The atom immediately releases red light when
the electron falls back from B back to C.
Many electron movements are happening simultaneously but only some of the
energy given back is expressed as visible light. Each element has a characteristic color of
visible light associated with the energy released when the electrons return to the lower
energy levels.
The flame lab lets you see some of the beautiful colors of copper (II), lithium,
sodium, manganese (II), strontium, potassium, iron, and magnesium ions.
B
A
C
nucleus
2
Chemistry Laboratory Data Sheet
Flame Tests for Identifying Elements
No.
Compound Name
1
Sodium Chloride
Table Salt
NaCl
Strontium Chloride
2
4
SrCl2
Potassium Chloride
Salt Substitute
KCl
Copper Chloride
5
CuCl2
Lithium Chloride
6
LiCl
Iron Powder
7
Fe
Copper Sulfate
8
CuSO4
Strontium Nitrate
3
9
10
11
Observations
Sr(NO3)2
Sodium Bicarbonate
Baking Soda
NaHCO3
Magnesium Powder
Flash Powder
Mg
Manganese Chloride
MnCl2
3