Question

See the General ChemistryNow CD-ROM or website, Screen 7.1 Chemical Puzeler. This screen shows that light of different colors can come from a "neon" sign or from certain salts when they are placed in a burning organic liquid. ("Neon" signs are glass tubes filled with neon, argon, and other gases, and the gases are excited by an electric current. They are very similar in this regard to common fluorescent lights, although the light in fluorescent tubes comes from the phosphor that coats the inside of the tube.) What do these two sources of light have in common? How is the light generated in each case?

Name: Problem 78, Chapter 7: Chemistry and Chemical Reactivity
Uploaded: 2020-06-04T01:00:55-08:00
Duration: 52 s
Channel: Edward Zhang

   See the General ChemistryNow CD-ROM or website, Screen 7.1 Chemical Puzeler. This screen shows that light of different colors can come from a "neon" sign or from certain salts when they are placed in a burning organic liquid. ("Neon" signs are glass tubes filled with neon, argon, and other gases, and the gases are excited by an electric current. They are very similar in this regard to common fluorescent lights, although the light in fluorescent tubes comes from the phosphor that coats the inside of the tube.) What do these two sources of light have in common? How is the light generated in each case?

Chemistry and Chemical Reactivity

John C. Kotz, Paul… 6th Edition

Chapter 7, Problem 78

Instant Answer

Solved by Expert Edward Zhang

06/04/2020

Step 1

In both cases, energy is absorbed by the atoms or molecules, causing their electrons to move to higher energy levels. When these excited electrons return to their original, lower energy levels, they release energy in the form of light. The color of the light Show more…

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See the General ChemistryNow CD-ROM or website, Screen 7.1 Chemical Puzeler. This screen shows that light of different colors can come from a "neon" sign or from certain salts when they are placed in a burning organic liquid. ("Neon" signs are glass tubes filled with neon, argon, and other gases, and the gases are excited by an electric current. They are very similar in this regard to common fluorescent lights, although the light in fluorescent tubes comes from the phosphor that coats the inside of the tube.) What do these two sources of light have in common? How is the light generated in each case?

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Key Concepts

Quantized Energy Levels

Atoms and molecules have discrete energy levels, and electrons can only occupy specific states. When electrons are excited to higher levels and then fall back to lower levels, they emit photons with energies corresponding to the difference between these levels, which manifests as light.

Electronic Transitions

Light generation in both cases involves electrons moving from higher to lower energy states. In both neon signs and flame tests, electrons are excited (by either an electric current or thermal energy) and then release energy as visible light during their return to a lower energy state.

Energy Excitation Mechanisms

Although the sources of energy differ—electrical discharge in neon signs and thermal energy in flaming organic liquids—the key commonality is the excitation of electrons. This excitation initiates the process of electronic transitions that result in the emission of light.

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