Organic Chemistry - Structure and Bonding Vocabulary

Vocabulary flashcards covering core terms and concepts of Chapter 1: Structure and Bonding in Organic Chemistry.

Organic Chemistry

The branch of chemistry devoted to the study of carbon compounds.

Heteroatoms

Atoms other than carbon and hydrogen that are incorporated into organic rings or carbon chains.

Octet Rule

The principle stating that atoms tend to gain, lose, or share electrons until they are surrounded by eight valence electrons, achieving a noble gas configuration.

Valence Electrons

Electrons residing in the outermost shell of an atom that are gained, lost, or shared during chemical reactions.

Electronegativity

The measure of the ability of an atom in a molecule to attract electrons toward itself.

Ionic Bond

A chemical bond formed by electrostatic attraction holding ions together, created by the transfer of electrons between atoms with an electronegativity difference greater than $1.9$.

Covalent Bond

A chemical bond formed when electron pairs are shared between two atoms whose difference in electronegativity is $1.9$ or less.

Nonpolar Covalent Bond

A covalent bond formed when the electronegativity difference between bonded atoms is less than $0.5$, typically occurring between two nonmetals or a nonmetal and a metalloid.

Polar Covalent Bond

A covalent bond formed when the electronegativity difference between bonded atoms is between $0.5$ and $1.9$.

Formal Charge

The charge assigned to an atom in a molecule or polyatomic ion, calculated as: $\text{Formal charge} = (\text{group number}) - (\text{number of unshared electrons}) - (\text{number of bonds})$.

Constitutional Isomers

Different compounds that share the same molecular formula but have different atom connectivities, resulting in distinct physical properties.

Stereoisomerism

A class of isomers in which molecules have the same atom connectivity but differ in the spatial orientation of their atoms.

VSEPR Model

The Valence-Shell Electron-Pair Repulsion model, which predicts molecular geometry by arranging electron domains around a central atom to minimize mutual repulsions.

Hybridization

The mixing or combining of different atomic orbitals ($s$, $p$, $d$, $f$) on an atom to form a new set of equivalent hybrid atomic orbitals.

Sigma ($\sigma$) Bond

A covalent bond formed by the head-to-head overlap of atomic orbitals, where electron density is concentrated symmetrically along the internuclear axis.

Pi ($\pi$) Bond

A covalent bond formed by the side-to-side overlap of parallel $p$ atomic orbitals, where electron density lies above and below the plane of the internuclear axis.

$sp^3$ Hybrid Orbitals

Hybrid orbitals formed by combining one $s$ orbital and three $p$ orbitals, producing four equivalent orbitals directed toward the vertices of a tetrahedron with bond angles of $109.5^\circ$.

$sp^2$ Hybrid Orbitals

Hybrid orbitals formed by combining one $s$ orbital and two $p$ orbitals, producing three equivalent orbitals in a trigonal planar geometry with bond angles of $120^\circ$.

$sp$ Hybrid Orbitals

Hybrid orbitals formed by combining one $s$ orbital and one $p$ orbital, producing two equivalent linear orbitals with a bond angle of $180^\circ$.

Dipole Moment

The vector sum of individual bond dipoles in a polyatomic molecule that determines the overall polarity of the molecule.

Nonpolar Compounds

Molecules in which the electron charge distribution is symmetrical across the entire structure, resulting in no net dipole moment.

Polar Compounds

Molecules in which the electron charge distribution is asymmetrical, creating a net overall dipole moment.

Resonance Structures

Two or more valid Lewis structures used to represent a molecule whose true electronic structure is a hybrid blend of these extreme representations.

Resonance Hybrid

The actual physical structure of a molecule with delocalized electrons, which represents a weighted average or blend of all valid resonance contributors.

Resonance Energy

A quantitative measure of the extra stability gained by a molecule as a result of electron delocalization across resonance contributors.