Chemical Bonding & Molecular Structure – Vocabulary Flashcards

Key vocabulary covering bonding theory, molecular geometry, intermolecular forces, and crystal structures as presented in the lecture notes.

Valence Electron

An electron in the highest occupied energy level of an atom; involved in chemical bonding.

Bonding Electron

A single (unpaired) valence electron that can be shared or transferred during bond formation.

Lone Pair

Two valence electrons occupying the same orbital that are NOT involved in bonding.

Octet Rule

Tendency of main-group atoms to achieve eight electrons in their valence shell when bonding.

Lewis Symbol

Element symbol surrounded by dots that represent an atom’s valence electrons.

Structural (Line) Formula

Diagram that shows which atoms are bonded to which using dashes for covalent bonds.

Stereochemical Formula

A structural formula drawn to represent the three-dimensional shape of a molecule.

Empirical Formula

Chemical formula showing the simplest whole-number ratio of atoms or ions in a substance.

Molecular Formula

Formula that lists the actual number of each type of atom present in one molecule.

Lewis Formula

A structure using Lewis symbols to display all valence electrons and covalent bonds in a molecule or ion.

Bonding Capacity

Maximum number of single covalent bonds an atom can form, equal to its number of bonding electrons.

Electronegativity

Numerical measure of an atom’s ability to attract shared electrons in a covalent bond.

Covalent Bond

Simultaneous attraction of two nuclei for a shared pair of valence electrons.

Ionic Bond

Electrostatic attraction between oppositely charged ions formed by electron transfer.

Metallic Bond

Attraction between metal cations and a ‘sea’ of mobile valence electrons in a metal crystal.

VSEPR Theory

Valence-Shell-Electron-Pair-Repulsion theory; predicts molecular shape by assuming electron pairs repel and arrange as far apart as possible.

Polar Covalent Bond

Covalent bond with unequal electron sharing due to a difference in electronegativity (δ+ and δ– ends).

Non-polar Covalent Bond

Covalent bond with equal electron sharing because bonding atoms have identical or very similar electronegativity.

Bond Dipole

Vector representing the separation of charge in a polar bond; points from δ+ to δ–.

Polar Molecule

Molecule whose bond dipoles do not cancel, resulting in an overall molecular dipole.

Non-polar Molecule

Molecule in which bond dipoles cancel, giving no overall molecular dipole.

Intermolecular Force

Attractive force acting between separate molecules, weaker than covalent or ionic bonds.

London (Dispersion) Force

Weak intermolecular attraction caused by simultaneous, momentary dipoles in adjacent molecules; present in all substances.

Dipole–Dipole Force

Attraction between the partial charges of permanent dipoles in polar molecules.

Hydrogen Bond

Strong dipole attraction where H bonded to N, O, or F is attracted to a lone pair on N, O, or F in another molecule.

Crystal Lattice

Regular, repeating three-dimensional arrangement of particles (ions, atoms, or molecules) in a solid.

Covalent Network Crystal

Solid where atoms are joined by a continuous network of covalent bonds (e.g., diamond, SiO₂).

Metallic Crystal

Solid consisting of closely packed metal ions surrounded by mobile electrons, giving metals their characteristic properties.

Isoelectronic Molecules

Different molecules or ions that contain the same total number of electrons.

Coordinate Covalent Bond

Covalent bond in which both electrons of the shared pair originate from the same atom.