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Ch.5 - Periodicity & Electronic Structure of Atoms
Chapter 5, Problem 57

Sodium-vapor lamps are a common source of lighting. The emission spectrum from this type of lamp is shown. Is this a continuous or line emission spectrum?Emission spectrum of sodium-vapor lamp showing light intensity at various wavelengths.

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1
Observe the emission spectrum provided in the image.
Note the presence of distinct lines at specific wavelengths (e.g., around 450 nm, 550 nm, and 600 nm).
Understand that a continuous spectrum would show a smooth gradient of colors without distinct lines.
Recognize that a line emission spectrum consists of discrete lines at specific wavelengths, corresponding to the emission of photons by electrons transitioning between energy levels in atoms.
Conclude that the given spectrum is a line emission spectrum because it shows distinct lines at specific wavelengths rather than a continuous range of wavelengths.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Emission Spectrum

An emission spectrum is produced when atoms or molecules emit light at specific wavelengths as they transition from a higher energy state to a lower one. Each element has a unique emission spectrum, which consists of distinct lines corresponding to the wavelengths of light emitted. This spectrum can be used to identify the presence of specific elements in a sample.
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Emission Spectra

Line vs. Continuous Spectrum

A line emission spectrum consists of discrete lines at specific wavelengths, indicating the presence of particular elements, while a continuous spectrum displays a smooth range of wavelengths without gaps. In the case of sodium-vapor lamps, the emitted light produces a line spectrum due to the quantized energy transitions of sodium atoms, which can be visually represented as sharp peaks in the spectrum.
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Electromagnetic Spectrum

Sodium Vapor Lamps

Sodium vapor lamps are a type of gas discharge lamp that emits light by passing an electric current through vaporized sodium. These lamps are known for their characteristic yellow-orange light and are commonly used in street lighting. The emission spectrum of sodium vapor lamps primarily features strong lines in the yellow region, which are indicative of the sodium element's specific energy transitions.
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