Dr. May – Integrated Science 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 crosscontamination 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
Integrated Science 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