Chapter 3: Electronic Structure and Periodic Properties – Vocabulary Flashcards

Vocabulary flashcards covering key terms from electromagnetic energy through the periodic table and bonding concepts as discussed in the lecture notes.

Electromagnetic energy

Energy carried by electromagnetic radiation, dependent on wavelength and frequency; travels at the speed of light and spans the electromagnetic spectrum.

Wave-particle duality

Principle that light and matter exhibit both wave-like and particle-like properties, a cornerstone of quantum theory.

Wavelength (λ)

Distance between successive peaks of a wave; for electromagnetic waves in vacuum, λν = c, linking wavelength and frequency.

Frequency (ν)

Number of wave cycles per second; measured in hertz (Hz); inversely related to wavelength in the relation λν = c.

Speed of light (c)

Constant speed at which electromagnetic waves travel in vacuum: approximately 2.998×10^8 m/s.

Planck's constant (h)

Proportionality constant in quantum relations, h ≈ 6.626×10^-34 J·s; relates energy to frequency via E = hν.

Photon

Quantum of light; a particle-like packet of energy E = hν that exhibits wavelike properties.

Blackbody radiation

Idealized spectrum of radiation emitted by a perfect absorber; explained by quantized energy and Planck’s law.

Ultraviolet catastrophe

Classical prediction of infinite radiative energy at short wavelengths; resolved by Planck’s quantization.

Photoelectric effect

Emission of electrons from a material (often a metal) when exposed to light above a threshold frequency; evidence for photons.

Einstein's photon explanation

Idea that light consists of photons with energy E = hν; explains the photoelectric effect and quantization of light.

De Broglie wavelength

Wavelength associated with a massive particle: λ = h/p, where p = mv; extends wave-particle duality to matter.

Schrödinger equation

Quantum-mechanical equation describing how the wavefunction evolves; foundational to the quantum mechanical model.

Wavefunction (ψ)

Mathematical function whose magnitude squared, |ψ|^2, gives the probability density of finding a particle in space.

Probability density

Square of the wavefunction magnitude, |ψ|^2, representing the likelihood of locating a particle in a region.

Principal quantum number (n)

Integer that designates the energy level (shell) of an electron; n = 1, 2, 3, …; determines overall size and energy.

Angular momentum quantum number (l)

Subshell type within a given n; l = 0, 1, …, n−1; defines orbital shape (s, p, d, f).

Magnetic quantum number (ml)

Orientation of an orbital within a subshell; ml ∈ [−l, l], giving the number of orbitals in a subshell (2l+1).

Spin quantum number (ms)**

Intrinsic spin of an electron; ms = +½ or −½; two electrons per orbital with opposite spins.

Radial node

Point where the radial part of the wavefunction is zero; number of radial nodes equals n − l − 1.

s, p, d, f orbitals

Types of atomic orbitals with shapes: s (spherical), p (dumbbell), d and f (more complex); correspond to l = 0, 1, 2, 3 respectively.

Hund’s rule

Within a set of degenerate orbitals, the most stable arrangement has the maximum number of unpaired electrons.

Aufbau principle

Rule for building electron configurations by filling lowest-energy subshells first.

Pauli exclusion principle

No two electrons in an atom can have the same set of all four quantum numbers (n, l, ml, ms).

Ground state

Lowest energy arrangement of electrons in an atom.

Hydrogen-like atoms

Atoms or ions with a single electron (e.g., H, He+, Li2+); energies scale with nuclear charge Z.

Bohr model

Early atomic model with quantized electron orbits; linked to emission/absorption spectra and the Rydberg formula.

Bohr radius (a0)

A0 = 5.292×10^-11 m; the radius of the ground-state (n=1) hydrogen orbital.

Rydberg constant (R∞)

Constant used in spectral formulae for hydrogen; relates to the energy differences between levels.

Ionization energy (IE1)

Energy required to remove the first electron from a gaseous atom; endothermic process.

Shielding

Electron-electron repulsion that reduces the effective nuclear charge felt by outer electrons.

Effective nuclear charge (Zeff)

Net positive charge experienced by valence electrons; Zeff = Z − shielding; influences orbital energies and radii.

Covalent radius

One-half the distance between nuclei in a covalently bonded diatomic molecule; practical size measure.

Ionic radius

Size of an ion; cations are smaller than their neutral atoms, anions larger; trends vary with group and charge.

Electron affinity (EA)

Energy change when an electron is added to a gaseous atom to form an anion; can be exothermic (negative EA) or endothermic (positive EA).

Periodic law

Properties of elements are periodic functions of their atomic numbers.

Periodic table

Organization of elements by increasing atomic number into seven periods and 18 groups; groups show similar properties.

Main-group elements

Elements whose outermost electron enters an s or p orbital; representative elements (groups 1,2,13–18).

Transition metals

Elements whose last electron enters a d orbital; characterized by partially filled d subshells.

Inner transition metals

Elements with last electron entering an f orbital; includes the lanthanide and actinide series.