Key Terms

Key Terms

angular momentum orbital quantum number (l)

quantum number associated with the orbital angular momentum of an electron in a hydrogen atom

angular momentum projection quantum number (m)

quantum number associated with the z-component of the orbital angular momentum of an electron in a hydrogen atom

atomic orbital

region in space that encloses a certain percentage (usually 90%) of the electron probability

Bohr magneton

magnetic moment of an electron, equal to $9.3\times {10}^{\mathrm{-24}}\text{J/T}$ or $5.8\times {10}^{\mathrm{-5}}\text{eV}\text{/}\text{T}$

braking radiation

radiation produced by targeting metal with a high-energy electron beam (or radiation produced by the acceleration of any charged particle in a material)

chemical group

group of elements in the same column of the periodic table that possess similar chemical properties

coherent light

light that consists of photons of the same frequency and phase

covalent bond

chemical bond formed by the sharing of electrons between two atoms

electron configuration

representation of the state of electrons in an atom, such as $1s^{2}2s^1$ for lithium

fine structure

detailed structure of atomic spectra produced by spin-orbit coupling

fluorescence

radiation produced by the excitation and subsequent, gradual de-excitation of an electron in an atom

hyperfine structure

detailed structure of atomic spectra produced by spin-orbit coupling

ionic bond

chemical bond formed by the electric attraction between two oppositely charged ions

laser

coherent light produced by a cascade of electron de-excitations

magnetic orbital quantum number

another term for the angular momentum projection quantum number

magnetogram

pictoral representation, or map, of the magnetic activity at the Sun’s surface

metastable state

state in which an electron “lingers” in an excited state

monochromatic

light that consists of photons with the same frequency

Moseley plot

plot of the atomic number versus the square root of X-ray frequency

Moseley’s law

relationship between the atomic number and X-ray photon frequency for X-ray production

orbital magnetic dipole moment

measure of the strength of the magnetic field produced by the orbital angular momentum of the electron

Pauli’s exclusion principle

no two electrons in an atom can have the same values for all four quantum numbers $(n,l,m,m_s)$

population inversion

condition in which a majority of atoms contain electrons in a metastable state

principal quantum number (n)

quantum number associated with the total energy of an electron in a hydrogen atom

radial probability density function

function use to determine the probability of a electron to be found in a spatial interval in r

selection rules

rules that determine whether atomic transitions are allowed or forbidden (rare)

spin projection quantum number ($m_s$)

quantum number associated with the z-component of the spin angular momentum of an electron

spin quantum number (s)

quantum number associated with the spin angular momentum of an electron

spin-flip transitions

atomic transitions between states of an electron-proton system in which the magnetic moments are aligned and not aligned

spin-orbit coupling

interaction between the electron magnetic moment and the magnetic field produced by the orbital angular momentum of the electron

stimulated emission

when a photon of energy triggers an electron in a metastable state to drop in energy emitting an additional photon

transition metal

element that is located in the gap between the first two columns and the last six columns of the table of elements that contains electrons that fill the d subshell

valence electron

electron in the outer shell of an atom that participates in chemical bonding

Zeeman effect

splitting of energy levels by an external magnetic field