University Physics Volume 3

# 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 $9.3×10−24J/T9.3×10−24J/T$ or $5.8×10−5eV/T5.8×10−5eV/T$
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 $1s22s11s22s1$ 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 $(n,l,m,ms)(n,l,m,ms)$
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
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 ($msms$)
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