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Chemistry LibreTexts

6.7: Key Terms

  • Page ID
    452742
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    Example and Directions
    Words (or words that have the same definition)The definition is case sensitive(Optional) Image to display with the definition [Not displayed in Glossary, only in pop-up on pages](Optional) Caption for Image(Optional) External or Internal Link(Optional) Source for Definition
    (Eg. "Genetic, Hereditary, DNA ...")(Eg. "Relating to genes or heredity")The infamous double helix https://bio.libretexts.org/CC-BY-SA; Delmar Larsen
    Glossary Entries
    Word(s)DefinitionImageCaptionLinkSource
    amplitudeextent of the displacement caused by a wave    
    atomic orbitalmathematical function that describes the behavior of an electron in an atom (also called the wavefunction)    
    Aufbau principleprocedure in which the electron configuration of the elements is determined by “building” them in order of atomic numbers, adding one proton to the nucleus and one electron to the proper subshell at a time    
    blackbodyidealized perfect absorber of all incident electromagnetic radiation; such bodies emit electromagnetic radiation in characteristic continuous spectra called blackbody radiation    
    Bohr’s model of the hydrogen atomstructural model in which an electron moves around the nucleus only in circular orbits, each with a specific allowed radius    
    continuous spectrumelectromagnetic radiation given off in an unbroken series of wavelengths (e.g., white light from the sun)    
    core electronelectron in an atom that occupies the orbitals of the inner shells    
    covalent radiusone-half the distance between the nuclei of two identical atoms when they are joined by a covalent bond    
    d orbitalregion of space with high electron density that is either four lobed or contains a dumbbell and torus shape; describes orbitals with l = 2.    
    degenerate orbitalsorbitals that have the same energy    
    effective nuclear chargecharge that leads to the Coulomb force exerted by the nucleus on an electron, calculated as the nuclear charge minus shielding    
    electromagnetic radiationenergy transmitted by waves that have an electric-field component and a magnetic-field component    
    electromagnetic spectrumrange of energies that electromagnetic radiation can comprise, including radio, microwaves, infrared, visible, ultraviolet, X-rays, and gamma rays    
    electron affinityenergy change associated with addition of an electron to a gaseous atom or ion    
    electron configurationlisting that identifies the electron occupancy of an atom’s shells and subshells    
    electron densitya measure of the probability of locating an electron in a particular region of space, it is equal to the squared absolute value of the wave function ψ    
    excited statestate having an energy greater than the ground-state energy    
    f orbitalmultilobed region of space with high electron density, describes orbitals with l = 3    
    frequency (ν)number of wave cycles (peaks or troughs) that pass a specified point in space per unit time    
    ground statestate in which the electrons in an atom, ion, or molecule have the lowest energy possible    
    Heisenberg uncertainty principlerule stating that it is impossible to exactly determine both certain conjugate dynamical properties such as the momentum and the position of a particle at the same time. The uncertainty principle is a consequence of quantum particles exhibiting wave–particle duality    
    hertz (Hz)the unit of frequency, which is the number of cycles per second, s−1    
    Hund’s ruleevery orbital in a subshell is singly occupied with one electron before any one orbital is doubly occupied, and all electrons in singly occupied orbitals have the same spin    
    intensityproperty of wave-propagated energy related to the amplitude of the wave, such as brightness of light or loudness of sound    
    interference patternpattern typically consisting of alternating bright and dark fringes; it results from constructive and destructive interference of waves    
    ionization energyenergy required to remove an electron from a gaseous atom or ion    
    isoelectronicgroup of ions or atoms that have identical electron configurations    
    line spectrumelectromagnetic radiation emitted at discrete wavelengths by a specific atom (or atoms) in an excited state    
    magnetic quantum number (ml)quantum number signifying the orientation of an atomic orbital around the nucleus    
    nodeany point of a standing wave with zero amplitude    
    orbital diagrampictorial representation of the electron configuration showing each orbital as a box and each electron as an arrow    
    p orbitaldumbbell-shaped region of space with high electron density, describes orbitals with l = 1    
    Pauli exclusion principlespecifies that no two electrons in an atom can have the same value for all four quantum numbers    
    photonsmallest possible packet of electromagnetic radiation, a particle of light    
    principal quantum number (n)quantum number specifying the shell an electron occupies in an atom    
    quantizationlimitation of some property to specific discrete values, not continuous    
    quantum mechanicsfield of study that includes quantization of energy, wave-particle duality, and the Heisenberg uncertainty principle to describe matter    
    quantum numbernumber having only specific allowed values and used to characterize the arrangement of electrons in an atom    
    s orbitalspherical region of space with high electron density, describes orbitals with l = 0    
    secondary (angular momentum) quantum number (l)quantum number distinguishing the different shapes of orbitals; it is also a measure of the orbital angular momentum    
    shellatomic orbitals with the same principal quantum number, n    
    spin quantum number (ms)number specifying the electron spin direction, either or     
    standing wave(also, stationary wave) localized wave phenomenon characterized by discrete wavelengths determined by the boundary conditions used to generate the waves; standing waves are inherently quantized    
    subshellatomic orbitals with the same values of n and l    
    valence electronselectrons in the high energy outer shell(s) of an atom    
    valence shellhigh energy outer shell(s) of an atom    
    waveoscillation of a property over time or space; can transport energy from one point to another    
    wave-particle dualityobservation that elementary particles can exhibit both wave-like and particle-like properties    
    wavefunction (ψ)mathematical description of an atomic orbital that describes the shape of the orbital; it can be used to calculate the probability of finding the electron at any given location in the orbital, as well as dynamical variables such as the energy and the angular momentum    
    wavelength (λ)distance between two consecutive peaks or troughs in a wave    

    6.7: Key Terms is shared under a CC BY 4.0 license and was authored, remixed, and/or curated by LibreTexts.

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