Chapter 1 Review of General Chemistry: Electrons, Bonds, and Molecular Structure

Vocabulary flashcards covering core concepts from Chapter 1: electrons, bonds, orbitals, molecular geometry, polarity, and intermolecular forces.

Organic chemistry

Study of compounds containing carbon; focuses on electron flow in reactions.

Bond

The force that holds atoms together, arising from sharing electrons (covalent) or electrostatic attraction.

Valence electrons

Electrons in the outermost shell used for bonding; count often equals the group number.

Lewis structure

Diagram showing valence electrons as dots and bonding/lone pairs to illustrate octets.

Formal charge

Charge assigned to atoms in a molecule based on valence electrons vs assigned electrons.

Anion

Negatively charged ion.

Cation

Positively charged ion.

Electronegativity

Tendency of an atom to attract shared electrons; fluorine is the most electronegative.

Polar covalent bond

Covalent bond with unequal sharing of electrons due to electronegativity difference (roughly 0.5–1.7).

Nonpolar covalent bond

Covalent bond with very small electronegativity difference (<0.5).

Ionic bond

Bond formed by transfer of electrons, yielding oppositely charged ions.

Bond-line structure

Shorthand depiction of carbon skeleton where corners/ends are carbon and hydrogens are implied.

Atomic orbitals

Regions in space where electrons are likely to be found (e.g., s, p); each orbital holds up to 2 electrons.

Orbital

Region of space described by quantum numbers where an electron is probable.

Principal quantum number (n)

Energy level of an electron within an atom.

Angular momentum quantum number (l)

Orbital type (s, p, d, f) describing orbital shape.

Magnetic quantum number (m_l)

Orientation of an orbital in space.

Spin quantum number (m_s)

Electron spin orientation (+1/2 or -1/2).

Electron configuration

Arrangement of electrons in orbitals; fills 1s, 2s, 2p, etc., following energy order.

Bonding molecular orbital (MO)

MO formed by in-phase overlap of atomic orbitals; stabilizes the system.

Antibonding molecular orbital (MO)

MO with a node that raises energy when occupied.

HOMO

Highest Occupied Molecular Orbital—the topmost MO that contains electrons.

LUMO

Lowest Unoccupied Molecular Orbital—the next available energy level.

Molecular Orbital Theory

Model where electrons occupy MOs formed from overlaps of atomic orbitals.

Hybridization

Mixing of atomic orbitals to form degenerate, equivalent hybrid orbitals for bonding.

sp3

Four equivalent hybrid orbitals arranged tetrahedrally; carbon in CH4.

sp2

Three sp2 hybrids plus one unhybridized p; planar geometry and enables double bonds.

sp

Two sp hybrids; linear geometry; used in triple bonds (ethyne).

Sigma bond

Bond formed by end-to-end overlap along the bond axis; typically strongest bond.

Pi bond

Bond formed by side-by-side overlap of p orbitals; part of double/triple bonds; weaker than sigma.

VSEPR theory

Valence Shell Electron Pair Repulsion; predicts molecular geometry from repulsion of electron pairs.

Steric number

Number of sigma bonds plus lone pairs around a central atom; determines hybridization.

Molecular geometry

Three-dimensional arrangement of bonded atoms around a central atom (e.g., linear, trigonal planar, tetrahedral).

Dipole moment

Measure of polarity; product of charge separation and distance between charges; unit: Debye.

Polar vs. nonpolar solubility rule

Like dissolves like: polar compounds mix with polar solvents; nonpolar with nonpolar.

Hydrogen bonding

Strong dipole-dipole attraction between a hydrogen attached to N, O, or F and a lone pair on another electronegative atom.

Protic solvent

Solvent that can donate H-bonds (has accessible protons for bonding).

Aprotic solvent

Solvent that cannot donate H-bonds.

London dispersion forces

Temporary dipole-induced dipole attractions; stronger with larger surface area; reduced by branching.

Dipole-dipole attractions

Intermolecular forces between polar molecules aligning charges oppositely.

Isomers (constitutional)

Compounds with the same molecular formula but different connectivity.

Micelles

Spherical assemblies of soap in water with a nonpolar interior that solubilizes dirt.

Solubility

Ability of a substance to dissolve; “like dissolves like” guides polar vs nonpolar mixing.

Octet rule

Second-row elements tend to achieve eight electrons around them in Lewis structures.

Lone pair

Nonbonding pair of valence electrons on an atom.