Chemical Bonding, Molecular Shape & Quantum Numbers

Vocabulary flashcards covering bonding types, molecular geometry concepts, quantum numbers, and electronic-configuration rules.

Ionic (Electrovalent) Bond

Electrostatic attraction between oppositely charged ions (cations and anions); non-directional.

Covalent Bond

Electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms; directional.

Metallic Bond

Attractive force between the lattice of positive metal ions and the sea of delocalized mobile electrons.

Characteristics of Ionic Compounds

High melting/boiling points, soluble in polar solvents, conduct electricity in molten/aqueous state (electrolytes), mostly solids at room temperature.

Characteristics of Covalent Compounds

Low melting/boiling points, insoluble in polar but soluble in non-polar solvents, non-electrolytes, often volatile liquids or gases at room temperature.

Lewis Structure

2-D diagram showing how atoms are bonded and how valence electrons are arranged; does not predict exact shape or bond angles.

Valence Shell Electron Pair Repulsion (VSEPR) Theory

Predicts 3-D molecular shape by assuming bonding and non-bonding electron pairs around a central atom repel to positions of minimum repulsion.

Lone-Pair Repulsion

Repulsive effect of non-bonding electrons, stronger than bonding-pair repulsion, causing bond-angle distortions in VSEPR geometries.

Atomic Orbital

Region around a nucleus with a high probability of finding an electron.

Principal Quantum Number (n)

Specifies the energy level/size of an orbital; n = 1, 2, 3 …

Azimuthal (Subsidiary) Quantum Number (l)

Indicates subshell shape; l ranges 0 to (n–1). l = 0 (s), 1 (p), 2 (d), 3 (f).

s-Orbital

Subshell with l = 0; spherical, one orbital, holds max 2 electrons.

p-Orbital

Subshell with l = 1; dumb-bell shape, three degenerate orbitals, holds max 6 electrons.

d-Orbital

Subshell with l = 2; double-dumbbell shape, five degenerate orbitals, holds max 10 electrons.

f-Orbital

Subshell with l = 3; complex shape, seven degenerate orbitals, holds max 14 electrons.

Degenerate Orbitals

Atomic orbitals within the same subshell that possess identical energies.

Magnetic Quantum Number (mₗ)

Specifies orbital orientation; values –l to +l, giving 2l + 1 possible orientations.

Spin Quantum Number (s)

Describes electron spin direction; +½ (clockwise) or –½ (anticlockwise).

Aufbau Principle

Electrons fill orbitals in order of increasing energy, from lowest to highest.

Hund’s Rule

Electrons occupy degenerate orbitals singly with parallel spins before pairing.

Pauli Exclusion Principle

No two electrons in the same atom can have identical sets of all four quantum numbers.

Electrolyte

Substance that conducts electricity in molten or aqueous form due to mobile ions.

Non-Electrolyte

Substance that does not conduct electricity in molten or aqueous form because ions are absent.

Polar Solvent

Highly polar liquid (e.g., water) that readily dissolves ionic compounds.

Non-Polar Solvent

Low-polarity liquid (e.g., benzene) that readily dissolves non-polar covalent substances.