Chapter U1.17, Problem 2E

Interpretation Introduction

Interpretation:

What is responsible for the colors during a flame test is to be explained.

Concept introduction:

Different compounds produce different colors in a flame test. Flame test is done by heating a small sample of a compound in a flame such as a Bunsen burner.

Answer to Problem 2E

During a flame test, the electrons get excited and move away from the nucleus. When these electrons move back to their original orbits they release energy in the form of colored light. This is responsible for the colors during a flame test.

Explanation of Solution

Each metal atom produces a specific color in the flame test. Non - metal atoms do not affect the color of the flame. When metal compounds are heated in a Bunsen burner, the atoms are not destroyed or new elements are not created. The flame of the burner does not change the nuclei of the atom. However, the heat is enough to impact the electrons of atoms.

When heated, the electrons get “excited” and are knocked off from their original places. They move away from the nucleus. This move is temporary. Soon they move back to their original place. In doing so, the electrons release energy in the form of colored light. This is what is responsible for the colors in the flame test.

Conclusion

Flame test is an important technique used in scientific laboratories to identify metal atoms in an unknown sample. It is quick and easy to perform. Each metal atom produces a specific color in the flame test. For example, lithium compounds produce red flame, barium produces green flame, sodium produces orange yellow, copper gives blue - green and calcium gives orange colored flame. Non - metal atoms do not affect the color of the flame.