The most prominent line in the emission spectrum of...

The most prominent line in the emission spectrum of magnesium is $285.2 \mathrm{nm} .$ Other lines are found at 383.8 and $518.4 \mathrm{nm}$. In what region of the electromagnetic spectrum are these lines found? Which is the most energetic line? What is the energy of $1.00 \mathrm{mol}$ of photons with the wavelength of the most energetic line?

Key Concepts

Electromagnetic Spectrum

The electromagnetic spectrum is the range of all types of electromagnetic radiation, which vary in wavelength and frequency. It includes regions such as gamma rays, X-rays, ultraviolet light, visible light, infrared radiation, microwaves, and radio waves. Each region is defined by a specific range of wavelengths and energies, and identifying the region of a given wavelength is crucial for understanding the properties and applications of the radiation.

Emission Spectrum

An emission spectrum is produced when atoms or molecules in an excited state release energy in the form of light as they return to lower energy states. The spectrum consists of distinct lines at specific wavelengths that correspond to the differences in energy levels within the atom or molecule. This concept is essential for analyzing the composition of substances and understanding atomic structure.

Photon Energy and Wavelength Relationship

The energy of a photon is inversely related to its wavelength, as described by the equation E = hc/?, where h is Planck’s constant and c is the speed of light. This means that photons with shorter wavelengths have higher energy compared to those with longer wavelengths. Recognizing this relationship allows one to determine which spectral lines correspond to higher energy transitions.

Mole and Avogadro's Number

A mole is a fundamental unit in chemistry used to express amounts of a chemical substance, containing approximately 6.022 x 10^23 entities (Avogadro's number). When calculating the energy associated with a given amount of photons, it is necessary to use Avogadro's number to convert the energy per photon to energy per mole, thereby allowing comparisons on a macroscopic scale.

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