Quantum Theory and Electronic Structure

Vocabulary flashcards covering key concepts of quantum theory, light behavior, atomic orbitals, quantum numbers, and electron configurations.

Wavelength ($\lambda$)

The distance between two consecutive peaks or troughs of a wave, expressed in units of meters ($m$).

Frequency ($\nu$)

The number of wave cycles per second that pass through a given point, expressed in units of $s^{-1}$ or Hertz ($Hz$).

Speed of Light ($c$)

The speed at which electromagnetic radiation travels through a vacuum, equal to $3.00 \times 10^8\,m/s$.

Amplitude ($A$)

The height of a wave from its midpoint to peak, which is classically related to the energy and intensity (brightness) of light.

Photoelectric Effect

The phenomenon in which electrons are ejected from a metal surface when light meeting a minimum threshold frequency strikes it.

Photons

Quantized packets or particles of energy that make up light, with energy defined by $E_{\text{photon}} = h\nu = \frac{hc}{\lambda}$.

Planck's Constant ($h$)

A fundamental constant equal to $6.626 \times 10^{-34}\,J\,s$ that relates the energy of a photon to its frequency.

Wave-Particle Duality

The property where light exhibits both wave and particulate characteristics, and matter (such as electrons) also exhibits both particulate and wave characteristics.

Wavefunction ($\Psi$)

A mathematical solution to the Schrödinger wave equation describing an atomic orbital.

Probability Density ($\Psi^2$)

The mathematical square of the wavefunction, representing the relative probability of finding an electron at any point around the nucleus.

Principal Quantum Number ($n$)

The quantum number that determines the size and main energy level of an orbital, taking integer values $n = 1, 2, 3, \dots$.

Angular Momentum Quantum Number ($\ell$)

The quantum number that specifies the shape of an orbital, taking integer values from $0$ to $n-1$.

Magnetic Quantum Number ($m_\ell$)

The quantum number that specifies the spatial orientation of an orbital, taking integer values from $-\ell$ to $+\ell$.

Electron Spin Quantum Number ($m_s$)

The quantum number describing the spin orientation of an electron, taking values of $+\frac{1}{2}$ or $-\frac{1}{2}$.

Pauli Exclusion Principle

The principle stating that no two electrons in an atom can have identical values for all four quantum numbers, limiting each orbital to two electrons with opposing spins.

Effective Nuclear Charge ($Z_{\text{eff}}$)

The net positive charge actually experienced by an electron in a multielectron atom, calculated as $Z_{\text{eff}} = Z_{\text{actual}} - \text{electron shielding}$.

Electron Shielding

The effect where inner electrons shield outer electrons from feeling the full positive charge of the nucleus.

Degenerate Orbitals

Orbitals that share the exact same energy level, such as subshells in single-electron hydrogen atoms.

Hund's Rule

The rule stating that when filling degenerate orbitals, electrons enter separate orbitals singly with parallel spins before pairing up.

Ground State Electron Configuration

The most stable, lowest-energy arrangement of electrons occupying atomic orbitals.

Atomic Radius Periodic Trend

The trend across the periodic table where atomic radius decreases across a period from left to right and increases down a group from top to bottom.