Organic Chemistry Fundamentals and Conformational Analysis

Vocabulary practice flashcards covering fundamental organic chemistry principles including chemical bonding, functional groups, resonance structures, acid-base theories, IUPAC alkane nomenclature, and conformational analysis of alkanes and cycloalkanes.

Tetravalent

Refers to an atom that generally forms four bonds, such as carbon.

Trivalent

Refers to an atom that generally forms three bonds, such as nitrogen.

Divalent

Refers to an atom that generally forms two bonds, such as oxygen.

Monovalent

Refers to an atom that generally forms one bond, such as hydrogen or halogens ($X = \text{F}, \text{Cl}, \text{Br}, \text{or } \text{I}$).

Vinylic Positions

The carbon atoms bearing a carbon-carbon double bond in a compound.

Allylic Positions

The atoms connected directly to vinylic positions (carbon atoms bearing a carbon-carbon double bond).

Five Patterns for Drawing Resonance Structures

The five fundamental structural patterns used to draw valid resonance forms: (1) allylic lone pair, (2) allylic carbocation, (3) lone pair adjacent to C+, (4) $\pi$ bond between two atoms of differing electronegativity, and (5) conjugated $\pi$ bonds enclosed in a ring.

Localized Lone Pair

A lone pair of electrons that resides in a single location on an atom and does not participate in resonance.

Delocalized Lone Pair

A lone pair of electrons that participates in resonance because it occupies a $p$ orbital capable of overlapping with neighboring $p$ orbitals.

Brønsted-Lowry Acid

A substance that acts as a proton ($H^+$) donor.

Brønsted-Lowry Base

A substance that acts as a proton ($H^+$) acceptor.

Conjugate Base

The species that remains after a Brønsted-Lowry acid donates a proton.

Conjugate Acid

The species formed after a Brønsted-Lowry base accepts a proton.

pKa

A logarithmic expression of acidity defined as $pKa = -\log K_a$, where a smaller or more negative value indicates a stronger acid.

ARIO

A mnemonic prioritization scheme standing for Atom, Resonance, Inductive effects, and Orbitals, used to evaluate the relative stability of anionic conjugate bases.

Hybrid Orbital Shapes

The distinct geometric shapes of $sp^3$, $sp^2$, and $sp$ hybrid orbitals, where higher $s$-character makes the orbital more spherical and holds electrons closer to the nucleus.

Leveling Effect

A solvent constraint dictating that the strongest base present in a solution cannot be stronger than the conjugate base of the solvent, and the strongest acid cannot be stronger than the conjugate acid of the solvent.

Counterions

Spectator cations (such as $Li^+$, $Na^+$, or $K^+$) that accompany negatively charged bases in solution without participating directly in electron flow mechanisms.

Lewis Acid

A substance defined as an electron-pair acceptor.

Lewis Base

A substance defined as an electron-pair donor.

Saturated Hydrocarbons

Hydrocarbons (alkanes) lacking $\pi$ bonds that possess the maximum possible number of hydrogen atoms relative to carbon atoms ($C_n H_{2n+2}$).

Substituents

Molecular branches or groups connected to the main parent chain of an organic molecule.

Cycloalkane

A saturated hydrocarbon containing a ring of carbon atoms with the general formula $C_n H_{2n}$.

Bridgeheads

The two carbon atoms in a bicyclic ring system where the individual rings are joined together.

Constitutional Isomers

Compounds that have the same molecular formula but differ in the connectivity of their atoms.

Heat of Combustion

The amount of heat given off ($-\Delta H^\circ$) when one mole of a compound undergoes complete combustion with oxygen to yield $CO_2$ and water.

Conformations

Temporary three-dimensional spatial arrangements of a molecule that result from rotation around single bonds.

Newman Projection

A diagrammatic representation of a molecular conformation looking directly down a specific carbon-carbon bond axis to observe front and back carbon substituents.

Dihedral Angle

The angle separating two specific bonds or atoms on adjacent carbons when viewed down the bond axis in a Newman projection.

Staggered Conformation

The lowest-energy molecular conformation wherein the bonds on the front carbon are separated by $60^\circ$ dihedral angles relative to the bonds on the back carbon.

Eclipsed Conformation

The highest-energy molecular conformation wherein the bonds on the front carbon directly align with the bonds on the back carbon ($0^\circ$ dihedral angle).

Degenerate Conformations

Two or more distinct spatial conformations of a molecule that share the exact same potential energy level.

Torsional Strain

The increase in potential energy caused by eclipsing interactions between bonds on adjacent atoms.

Anti Conformation

A staggered conformation in which the two largest or main substituents are oriented $180^\circ$ apart from each other.

Gauche Interaction

A type of steric strain occurring in a staggered conformation when two non-hydrogen groups are positioned at a $60^\circ$ dihedral angle to one another.

Angle Strain

The increase in potential energy when bond angles deviate from their ideal tetrahedral angle of $109.5^\circ$.

Chair Conformation

The most stable, nearly strain-free conformation of cyclohexane, characterized by tetrahedral bond angles ($109.5^\circ$) and staggered C-H bonds.

Boat Conformation

A high-energy conformation of cyclohexane featuring severe torsional strain from eclipsing hydrogens and steric strain from flagpole interactions.

Cyclohexane Conformational Energy Diagram

An energy profile mapping cyclohexane conformations by potential energy, ranking chair as the lowest energy state, followed by twist boat, boat, and half-chair as the highest energy state.

Axial Positions

Substituent positions on a chair cyclohexane ring that point straight up or straight down, parallel to a vertical axis passing through the ring's center.

Equatorial Positions

Substituent positions on a chair cyclohexane ring that extend outward around the equator of the ring, angled slightly up or down.

Ring Flip

A conformational interconversion of cyclohexane accomplished via rotation about C-C single bonds, converting all axial positions to equatorial and all equatorial positions to axial.

1,3-Diaxial Interactions

Steric strain resulting from interactions between an axial substituent on a cyclohexane chair and axial hydrogen atoms or groups located two carbons away on the same side of the ring.

cis-trans Stereoisomers

Stereoisomers differing in the spatial arrangement of substituents relative to a ring or double bond, where cis signifies groups on the same side and trans signifies groups on opposite sides.