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A comprehensive set of vocabulary-style flashcards covering key topics from general chemistry, inorganic/organic chemistry, and medicinal chemistry as presented in the lecture notes. Each card defines a term and explains its relevance to PhLE exam topics.
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Matter
Anything that has mass and occupies space; the basic subject of chemistry.
Atom
The basic unit of an element that retains the properties of that element; composed of protons, neutrons, and electrons.
Element
A pure substance made of one kind of atom that cannot be broken down by simple chemical means.
Compound
A substance formed by chemically joining two or more elements in fixed proportions.
Mixture
Matter composed of two or more substances not chemically bonded; can be homogeneous or heterogeneous.
Homogeneous Mixture
A uniform mixture with one phase (e.g., solution).
Heterogeneous Mixture
A mixture with two or more distinct phases.
Law of Definite Proportions
Elements in a compound combine in fixed whole-number ratios.
Law of Multiple Proportions
Elements can combine in different ratios to form different compounds.
Law of Conservation of Mass
In a chemical reaction, mass is conserved; total mass of reactants equals total mass of products.
Physical Change
A change in matter that alters form but not chemical identity (e.g., phase change).
Chemical Change
A process that forms new substances with new properties; evidenced by gas evolution, precipitate, heat, or color change.
Phase/State
Solid, liquid, gas; plasmas and, in some contexts, liquid crystals as a mesophase.
Colloid
A heterogeneous mixture with particles dispersed in a medium; larger than in solutions but smaller than in suspensions.
Tyndall Effect
Light scattering by colloidal particles, giving a visible beam in a colloid.
Brownian Movement
Random zigzag motion of colloidal particles due to collisions with molecules.
Electrophoresis
Movement of charged particles through a medium under an electric field.
SDS-PAGE
A gel electrophoresis technique used to separate proteins and nucleic acids by size.
Covalent Bond
A bond formed by the sharing of electron pairs between atoms.
Ionic Bond
A bond formed by electrostatic attraction between oppositely charged ions.
Hydrogen Bond
A strong dipole-dipole interaction involving hydrogen and a highly electronegative atom (N, O, F).
Van der Waals Forces
Weak intermolecular forces including London dispersion, dipole-dipole, and dipole-induced dipole attractions.
Dipole Moment
A measure of the separation of positive and negative charges in a molecule.
Electronegativity
Tendency of an atom to attract electrons in a chemical bond.
Ionization Energy
Energy required to remove an electron from a neutral atom in the gaseous state.
Electron Affinity
Energy change when an electron is added to a neutral atom to form an anion.
Periodic Table
A tabular arrangement of elements organized by increasing atomic number and periodic properties.
Group/Family
Column of the periodic table; elements share similar valence electron configurations.
Period
Row of the periodic table; elements show a progression of properties across the row.
Isotope
Atoms of the same element with the same number of protons but different numbers of neutrons.
Isobar
Different elements with the same atomic mass number but different atomic numbers.
Isotone
Different elements with the same number of neutrons.
Electron Configuration
Distribution of electrons among atomic orbitals in an atom.
Quantum Numbers
Numbers describing electron position: n (principal), l (azimuthal), ml (magnetic), ms (spin).
Pauli Exclusion Principle
No two electrons in an atom can have the same set of quantum numbers; each orbital holds at most 2 electrons.
Aufbau Principle
Electrons fill lowest energy levels first, building up to higher levels.
Hund’s Rule
Orbitals of the same subshell are singly occupied before pairing occurs.
Hund’s Rule of Maximum Multiplicity
Electrons fill degenerate orbitals singly before pairing.
Hybridization
Mixing of atomic orbitals (e.g., sp3, sp2, sp) to form new hybrid orbitals.
Sigma Bond (σ)
A single covalent bond formed by end-to-end overlap along the bond axis.
Pi Bond (π)
A covalent bond formed by side-by-side overlap of p orbitals; accompanies a σ bond in multiple bonds.
Molecular Orbital
A region in a molecule where electrons are most likely to be found; formed by overlapping atomic orbitals.
Valence Electrons
Electrons in the outermost shell that determine chemical reactivity.
Reaction Rate
Speed at which a chemical reaction proceeds.
Collision Theory
Reaction rate depends on the frequency and energy of molecular collisions.
Activation Energy (Ea)
Minimum energy required for reactants to transform into products.
Transition State
High-energy, unstable arrangement of atoms at the top of the reaction energy barrier.
Rate Law
Expression of the rate of reaction as a function of reactant concentrations; Rate = K[A]^x[B]^y.
Catalyst
Substance that speeds a reaction by providing an alternative pathway with lower Ea.
Le Chatelier’s Principle
A system at equilibrium responds to stresses (concentration, temperature, pressure) by shifting to counteract the stress.
Thermodynamics
Science of energy transformations and how energy affects matter and its properties.
System vs Surroundings
System is the part being studied; surroundings include everything else.
State Function
Path-independent properties (e.g., H, S, G) that depend only on the current state.
Non-State Function
Path-dependent quantities (e.g., work, heat) that depend on the process taken.
First Law of Thermodynamics
Energy cannot be created or destroyed; it can only be transformed.
Second Law of Thermodynamics
Spontaneous processes increase the total entropy of the universe.
Third Law of Thermodynamics
The entropy of a perfect crystal at absolute zero is zero.
Enthalpy (H)
Heat content of a system at constant pressure.
Entropy (S)
A measure of the degree of disorder or randomness of a system.
Gibbs Free Energy (G)
Energy that determines spontaneity; ΔG = ΔH − TΔS; ΔG = 0 at equilibrium.
Internal Energy (U)
Total energy contained within a system (thermal + chemical energy).
Heat (q)
Energy transferred due to temperature difference; positive if absorbed, negative if released.
Work (w)
Energy transfer due to pressure-volume work; sign depends on whether work is done by or on the system.
pH
A measure of hydrogen ion concentration; pH = −log[H+].
pOH
A measure of hydroxide ion concentration; pH + pOH = 14 at 25°C.
Buffer Capacity
Ability of a buffer to resist changes in pH upon addition of acid or base.
Henderson–Hasselbalch Equation
pH = pKa + log([salt]/[acid]); relates pH to buffer components.
Amphoteric Substance
A substance that can act as either an acid or a base.
Isohydric Solution
A solution with the same pH as a standard solution.
Solubility
Maximum amount of solute that can dissolve in a solvent at a given temperature.
Miscibility
Ability of two substances to mix in all proportions; form a homogeneous solution.
Raoult’s Law
Lowering of solvent vapor pressure is proportional to the mole fraction of solute.
Henry’s Law
Solubility of a gas in a liquid is proportional to the partial pressure of the gas.
Vapor Pressure Lowering
Decrease in solvent vapor pressure due to nonvolatile solute, a colligative property.
Boiling Point Elevation
Increase in boiling point caused by added solute (colligative property).
Freezing Point Depression
Lowering of freezing point due to solute presence (colligative property).
Osmotic Pressure
Pressure needed to prevent solvent flow across a semipermeable membrane.
Ideal Gas Law
PV = nRT; relates pressure, volume, temperature, and moles of gas.
Avogadro’s Law
Volume is directly proportional to the number of gas moles.
Boyle’s Law
Volume is inversely proportional to pressure (at fixed temperature and amount of gas).
Charles’s Law
Volume is directly proportional to temperature (in Kelvin) at constant pressure.
Grahams Law
Rate of effusion or diffusion is inversely proportional to the square root of molar mass.
Synthesis (Combination) Reaction
Direct union of elements to form a compound.
Decomposition Reaction
Complex substance breaks down into simpler substances.
Single Replacement Reaction
An element replaces another in a compound (A + BC → B + AC).
Double Replacement Reaction
Exchange of partners between two compounds (AB + CD → AD + CB).
Neutralization
Acid reacts with base to form a salt and water.
Redox (Oxidation-Reduction)
Reactions involving electron transfer; oxidation is loss of electrons, reduction is gain.
Lucas Test
Qualitative test for alcohols using ZnCl2 in HCl to differentiate 1°, 2°, 3° alcohols.
Alcohols
Hydroxyl-containing organic compounds (−OH); classified as primary, secondary, or tertiary.
Aldehydes & Ketones
Functional groups with carbonyl C=O; aldehydes have –CHO, ketones have C=O within the chain.
Carboxylic Acids
R–COOH; acidic organic acids; derivatives include esters, amides, anhydrides.
Esters
R–COOR; formed by reaction of carboxylic acids with alcohols; often have pleasant odors.
Amides
Derivatives of carboxylic acids with –CONR2; formed by condensation with amines.
Amines
Organic derivatives of ammonia (RNH2, R2NH, R3N); basic in nature.
IUPAC Nomenclature
Systematic naming of organic compounds using longest carbon chain, lowest locants, and suffix changes for functional groups.
Isomerism
Compounds with same molecular formula but different structures; includes structural, geometric, and stereoisomers.
Stereochemistry
Study of spatial arrangement of atoms; includes enantiomers, diastereomers, and epimers.
Optical Activity
Rotation of polarized light by chiral molecules; measured with a polarimeter.
Chirality/Chiral Center
A carbon atom bonded to four different groups; can have non-superimposable mirror images (enantiomers).