Chemical Bonding, Reactivity & Equilibrium – Key Vocabulary

Vocabulary flashcards summarizing bonding, intermolecular forces, oxidation–reduction reagents, hybridization, equilibrium concepts, photon energy, and nitrogen-containing functional groups from the lecture notes.

Polar Covalent Bond

Intramolecular bond with unequal sharing of electrons between atoms of different electronegativity (e.g., H₂O, NH₃).

Non-Polar Covalent Bond

Intramolecular bond with equal sharing of electrons; typically between identical atoms or C–H bonds (e.g., O₂, CH₄).

Ionic Bond

Chemical bond formed by complete electron transfer, producing oppositely charged ions.

Electronegativity Difference (≈0.5 rule)

Threshold used to distinguish non-polar (

Intermolecular Forces

Forces between molecules; weaker than intramolecular bonds.

Hydrogen Bond

Moderate intermolecular attraction between H bonded to N, O, or F and a lone pair on N, O, or F; vital in DNA and protein folding.

Dipole-Dipole Interaction

Moderate attraction between permanent dipoles of two polar molecules.

London Dispersion Force

Weak, temporary attractions due to instantaneous dipoles; present in all molecules, dominant in non-polar ones.

Van der Waals Force

General term encompassing dipole-dipole and London dispersion interactions.

Peptide (Amide) Bond

C(=O)–NH linkage connecting amino acids in proteins.

Disulfide Bond

Cys–S–S–Cys covalent link stabilizing protein tertiary structure.

Phosphodiester Bond

PO₄-linked connection between nucleotides in DNA/RNA backbones.

Hybridization sp

Atom with 2 electron groups; linear geometry; 180° bond angle.

Hybridization sp²

Atom with 3 electron groups; trigonal planar geometry; 120° bond angle.

Hybridization sp³

Atom with 4 electron groups; tetrahedral geometry; 109.5° bond angle.

Primary Alcohol

–CH₂OH group; can be oxidized to aldehyde (PCC) or further to carboxylic acid (strong oxidant).

Secondary Alcohol

–CHOH– group; oxidizes to ketone with mild or strong oxidants.

Tertiary Alcohol

C(OH) with no C–H on the carbon; cannot be oxidized under normal conditions.

PCC (Pyridinium Chlorochromate)

Mild oxidizing agent; stops at aldehydes or ketones without over-oxidation.

KMnO₄

Strong oxidizing agent; converts primary alcohols or aldehydes to carboxylic acids.

NaBH₄

Mild reducing agent; reduces aldehydes & ketones to alcohols but not carboxylic acids.

LiAlH₄ (LAH)

Strong reducing agent; reduces aldehydes, ketones, carboxylic acids, esters, and amides.

H₂ / Pd-C

Catalytic hydrogenation reagent; adds H₂ across π-bonds (alkenes/alkynes) and reduces many functional groups.

E / Z Nomenclature

‘E’ (entgegen) = opposite sides; ‘Z’ (zusammen) = same side orientation of substituents across a double bond.

Equilibrium Constant (K_eq)

Ratio of product to reactant activities at equilibrium, excluding solids and pure liquids.

Photon

Discrete particle of light carrying quantized energy.

Planck’s Constant (h)

6.63 × 10⁻³⁴ J·s; relates photon energy to frequency via E = hν.

Ground State

Lowest energy electron level (n = 1) in an atom.

Excited State

Higher energy electron level (n ≥ 2) reached after photon absorption.

Absorption (Atomic)

Process where electron gains energy and jumps to a higher level.

Emission (Atomic)

Electron loses energy, falls to lower level, and releases a photon.

Amide

Functional group with nitrogen directly bonded to a carbonyl; less basic than amines.

Amine

Nitrogen bonded to carbon(s) or H; acts as a base and electron pair donor.

Imine

C=N functional group formed from primary amine and carbonyl; electrophilic carbon.

Enamine

Alkene adjacent to an amine (C=C–N); nucleophilic at the α-carbon; formed from secondary amine and carbonyl.