Electronic Structure of Atoms – Chapter 6 Key Vocabulary

A comprehensive set of vocabulary flashcards summarizing the fundamental terms and definitions from Chapter 6: Electronic Structure of Atoms.

Electronic structure

The energies and arrangement of electrons around an atom.

Electromagnetic radiation (radiant energy)

Energy that travels through space at the speed of light, exhibiting both electric and magnetic wave components.

Speed of light (c)

A constant value of 2.998 \times 10^8 \text{ m s}^{-1} for electromagnetic radiation in a vacuum.

Wavelength (λ)

The distance between successive crests of a wave; commonly measured in meters.

Frequency (ν)

The number of wave cycles that pass a given point per second; measured in s^{-1} (hertz).

Wave equation (λν = c)

Relationship showing that the product of wavelength and frequency equals the speed of light.

Quantum of energy

The smallest discrete amount of energy that can be gained or lost by an atom, equal to E = hν.

Planck constant (h)

A fundamental constant valued at 6.626 \times 10^{-34} \text{ J s} relating energy and frequency.

Photon

A packet of electromagnetic energy carrying E = hν.

Photoelectric effect

Emission of electrons from a metal surface when light of sufficient frequency strikes it.

Spectrum

Display of component wavelengths of radiation separated by dispersion.

Continuous spectrum

A spectrum that contains all wavelengths without interruption.

Line spectrum

A spectrum showing only specific, discrete wavelengths emitted or absorbed by atoms.

Bohr model

Early atomic model in which electrons occupy circular orbits with quantized energies determined by the principal quantum number n.

Principal quantum number (n)

Positive integer (1, 2, 3,…) that specifies an orbital’s size and energy; n = 1 represents the ground state.

Ground state

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

Excited state

Any energy state of an atom with n > 1, higher than the ground state.

Matter waves (de Broglie hypothesis)

Concept that particles such as electrons possess wave properties with \lambda = h/(mv).

Heisenberg uncertainty principle

Statement that position (\Delta x) and momentum (\Delta mv) of a particle cannot both be known exactly; \Delta x \cdot \Delta(mv) \ge h/4\pi.

Wave function (ψ)

Mathematical description of an electron’s behavior; its square (\psi^2) gives probability density.

Probability density (ψ²)

Value proportional to the likelihood of finding an electron at a specific point in space.

Orbital

Allowed wave function of an electron in an atom, described by quantum numbers n, l, and m_l.

Angular momentum quantum number (l)

Integer from 0 to n − 1 that defines an orbital’s shape; denoted by letters s (0), p (1), d (2), f (3).

Magnetic quantum number (m_l)

Integer from −l to +l that specifies the orientation of an orbital in space.

Electron shell

Set of all orbitals with the same principal quantum number n.

Subshell

Set of orbitals with the same n and l values (e.g., 3p).

Degenerate orbitals

Orbitals within the same subshell that have identical energies.

Contour representation

Drawing that shows the shape of an orbital using surfaces of constant probability density.

Radial probability function

Graph that shows the probability of finding an electron at a specific distance from the nucleus.

Node

Region in space where the probability of finding an electron is zero.

Electron spin

Intrinsic property of electrons described by the spin magnetic quantum number (m_s = +½ or −½).

Pauli exclusion principle

Rule stating that no two electrons in an atom can share the same set of four quantum numbers.

Hund's rule

Principle that the lowest energy arrangement in a subshell is obtained by maximizing parallel electron spins in separate degenerate orbitals.

Electron configuration

Notation that shows the distribution of electrons among atomic orbitals in the ground state.

Orbital diagram

Pictorial representation of electron configuration using boxes (orbitals) and arrows (electrons).

Valence electrons

Outer-shell electrons involved in chemical bonding.

Core electrons

Electrons in an atom that are not part of the valence shell.

Representative (main-group) elements

Elements whose outermost electrons occupy s or p subshells.

Transition elements (transition metals)

Elements in which a d subshell is being filled.

Lanthanide elements

Elements in which the 4f subshell is being filled; part of the f-block metals.

Actinide elements

Elements in which the 5f subshell is being filled; included in the f-block metals.

f-block metals

Collective term for lanthanide and actinide elements in which f subshells are being filled.