Line Spectra and the Bohr Model Vocabulary

Vocabulary flashcards reviewing key terms, definitions, scientists, and constants related to atomic line spectra, the Bohr model, and atomic structure.

Cesium Clock

An atomic clock defined in 1967 based on the duration of $9,192,631,770$ oscillations of the resonant frequency of a cesium atom.

Lyman Series

A series of spectral lines in the emission spectrum of hydrogen corresponding to electron transitions from various excited states to the $n = 1$ orbit, occurring in the ultraviolet region.

Lyman Alpha

The strongest atomic emission line from the sun, produced by the transition from $n = 2$ to $n = 1$ in hydrogen with a wavelength of $122\,\text{nm}$ ($1.215 \times 10^{-7}\,\text{m}$) or wavenumber of $82,280\,\text{cm}^{-1}$.

Pfund Series

A series of lines in the emission spectrum of hydrogen corresponding to electron transitions from higher excited states to the $n = 5$ orbit, located in the infrared region of the spectrum.

Wavenumber

A unit expressed in inverse centimeters ($\text{cm}^{-1}$) commonly used in spectroscopy that is directly proportional to frequency and energy.

Emission Spectrum

A spectrum produced by the emission of light at specific wavelengths when atoms in excited states decay to lower-energy states.

Absorption Spectrum

A spectrum containing dark lines superimposed on a continuous spectrum, produced when ground-state or lower-energy atoms absorb light at specific frequencies.

Spectroscopy

The field of study that uses emission and absorption spectra to determine the structure and chemical composition of substances or astronomical objects.

Pierre Janssen

The French astronomer (1824–1907) who observed unassigned spectral lines during the solar eclipse of 1868, leading to the proposal and discovery of helium.

Alpha Particles

Helium nuclei emitted by radioactive uranium that capture surrounding electrons to form neutral helium atoms.

Ground State

The orbit closest to the atomic nucleus ($n = 1$), representing the lowest energy level and most stable state of an atom.

Excited State

Any orbit farther from the nucleus ($n \ge 2$) with higher energy than the ground state into which an electron moves upon absorbing energy.

Line Spectrum

A spectrum containing light emitted at only specific discrete wavelengths characteristic of individual elements, as opposed to a continuous spectrum produced by a hot object.

Sodium Emission Spectrum

An emission spectrum whose most intense lines occur at $589\,\text{nm}$, producing the characteristic yellow light in sodium street lamps.

Mercury Emission Spectrum

An emission spectrum where most emission lines occur below $450\,\text{nm}$, producing blue light in mercury discharge lamps.