Electronic Structure of the Atom Vocabulary

Vocabulary practice flashcards covering electronic structure of the atom, light properties, quantum numbers, periodic trends, and orbital mechanics.

Wavelength ($\lambda$)

The distance between two consecutive peaks or troughs in a wave.

Frequency ($\nu$)

The number of waves (cycles) per second that pass a given point in space.

Speed of Light ($c$)

The constant speed at which electromagnetic radiation travels through space, equal to $2.9979 \times 10^8\,\text{m/s}$.

Planck's Constant ($h$)

A fundamental physical constant with a value of $6.626 \times 10^{-34}\,\text{J}\cdot\text{s}$, used to relate wave frequency to quantum energy.

Quantum

A small, discrete unit of energy; system energy changes can occur only in whole-number multiples of quanta.

Photon

A stream of particle-like packets of electromagnetic radiation carrying energy defined by $E_{\text{photon}} = h\nu = \frac{hc}{\lambda}$.

Photoelectric Effect

The phenomenon in which electrons are emitted from the surface of a metal when light strikes it.

Threshold Frequency ($\nu_0$)

The minimum frequency of incident light below which no electrons are emitted from a specific metal surface.

Dual Nature of Light

The phenomenon whereby electromagnetic radiation and matter exhibit both wave properties and particulate properties.

de Broglie's Equation

An equation ($\lambda = \frac{h}{mv}$) used to calculate the wavelength associated with a particle based on its mass and velocity.

Diffraction

The scattering of light from a regular array of points or lines, producing an interference pattern of bright and dark areas.

Line Spectrum

A spectrum showing only discrete wavelengths of light, demonstrating that electron energy levels in an atom are quantized.

Bohr Model

A quantum model for the hydrogen atom postulating that electrons move around the nucleus only in specific allowed circular orbits.

Ground State

The lowest possible energy state of an atom ($n = 1$ for hydrogen).

Excited State

A state in which an atom possesses a higher energy level than its ground state after absorbing energy.

Standing Waves

Stationary waves that do not travel along any length, requiring specific circumferences to avoid destructive interference.

Wave Function ($\psi$)

A mathematical equation representing an orbital that describes the spatial coordinates of an electron's position.

Heisenberg Uncertainty Principle

A fundamental rule stating that both the position ($\Delta x$) and momentum ($\Delta(mv)$) of a particle cannot be precisely known simultaneously ($\Delta x \cdot \Delta(mv) \ge \frac{h}{4\pi}$).

Electron Density Map

A probability distribution diagram of $\psi^2$ where color intensity indicates the likelihood of finding an electron near a given point in space.

Radial Probability Distribution

A graph plotting the total probability of finding an electron in spherical shells against distance ($r$) from the nucleus.

Node (Nodal Surface)

A region or surface in an atomic orbital where the probability of finding an electron is zero.

Principal Quantum Number ($n$)

An integer value quantum number related to the overall size and primary energy level of an orbital.

Angular Momentum Quantum Number ($\ell$)

A quantum number taking integer values from $0$ to $n - 1$ that defines the shape of an atomic orbital subshell ($s, p, d, f$).

Magnetic Quantum Number ($m_\ell$)

A quantum number with integral values from $-\ell$ to $+\ell$ that describes the orientation of an orbital in 3D space.

Electron Spin Quantum Number ($m_s$)

A quantum number with values of $+\frac{1}{2}$ or $-\frac{1}{2}$ that designates the direction of an electron's spin.

Degenerate Orbitals

Atomic orbitals that belong to the same energy level.

Pauli Exclusion Principle

The rule stating that no two electrons in the same atom can have identical sets of all four quantum numbers.

Polyelectronic Atoms

Atoms containing more than one electron, which introduces electron-electron repulsion factors.

Penetration Effect

The ability of an electron in a given orbital (such as $2s$) to approach closer to the nucleus than electrons in other subshells (such as $2p$), lowering its overall energy.

Aufbau Principle

The rule that electrons fill atomic orbitals of lowest available energy levels before occupying higher levels.

Hund's Rule

The rule stating that the lowest energy electron configuration is the one with the maximum number of unpaired electrons in degenerate subshells.

Atomic Radius

A measure of atomic size obtained from interatomic distances; it decreases across a period from left to right and increases down a group.

Ionization Energy

The amount of energy required to remove an electron from a gaseous atom or ion in its ground state.

Electron Affinity

The energy change associated with adding an electron to a gaseous atom.

p Orbitals

Dumbbell-shaped atomic orbitals corresponding to $\ell = 1$ with two lobes separated by a node at the nucleus.

d Orbitals

Atomic orbitals corresponding to $\ell = 2$ that first appear in principal quantum level $n = 3$, featuring five distinct spatial shapes.