Comprehensive Science and Laboratory Review: Chemistry, Applied Calculations, Physics, and Organic Chemistry

Comprehensive practice flashcards covering fundamental chemistry, stoichometric and laboratory calculations, caloric physics and separation operations, and foundational organic chemistry mechanisms.

Particle Model (Teilchenmodell)

A fundamental physical model postulating that all matter consists of minuscule, spherical particles in continuous motion. Most substances exist as mixtures, whereas a pure substance represents a system with a very high concentration of a single type of particle.

Modifikation (Allotrope / Modification)

The existence of a single chemical element or pure substance in different solid crystalline or structural forms exhibiting distinct physical properties, exemplified by graphite and diamond for carbon.

Colloid (Kolloid)

A disperse system containing particle sizes ranging from $1\,nm$ to $100\,nm$ (an apparent solution or Scheinlösung), intermediate between coarse suspensions and true homogeneous solutions.

Tyndall Effect (Tyndall-Effekt)

The optical scattering of light by dispersed particles in a colloid, rendering the path of a light beam visible through the medium.

Law of Conservation of Mass (Massenerhaltung)

A fundamental law established by Lavoisier (1789) stating that in a closed chemical system, the total mass of the reactants (Edukte) equals the total mass of the products (Produkte).

Law of Definite Proportions (Konstante Proportionen)

A fundamental law formulated by Proust (1797) stating that the mass ratio of the chemical elements composing a given compound is always constant (for example, $NaCl$ is consistently $39\%$ $Na$ and $61\%$ $Cl$).

Law of Multiple Proportions (Multiple Proportionen)

A chemical law established by Dalton (1808) stating that if two elements combine to form more than one chemical compound, the varying masses of one element that combine with a fixed mass of the other stand in a ratio of small whole numbers.

Nuclide (Nuklid)

An atom characterized by a specific nuclear composition defined by its atomic number $Z$ (number of protons) and its mass number $A$ (total number of nucleons, protons plus neutrons).

Isotopes (Isotope)

Nuclides of the same chemical element sharing the exact same proton number ($Z$) and identical periodic table placement, but differing in their neutron count and mass number ($A$).

Bohr Atomic Model (1913)

An atomic model postulating that electrons revolve around a positively charged nucleus exclusively on discrete energy shells ($K, L, M, N, \dots$) without emitting radiation, where shell transitions occur via discrete quantum leaps and the maximum capacity per shell equals $2n^2$.

Atomic Mass Unit ($u$)

A standardized unit of mass defined as exactly $\frac{1}{12}$ of the mass of a single unbound $^{12}\text{C}$ carbon atom, numerically equal to $1.660539 \times 10^{-24}\,g$.

Mole (Mol)

The SI base unit for amount of substance ($n$), defined as containing exactly the Avogadro number of particles ($6.02214076 \times 10^{23}$), identical to the number of atoms present in $12\,g$ of $^{12}\text{C}$.

Octet Rule (Oktettregel)

The empirical chemical rule stating that atoms transfer or share valence electrons in order to achieve the stable electronic configuration of a noble gas, characterized by $8$ outer valence electrons (or $2$ for helium).

Brønsted Acid-Base Concept

A theoretical framework defining acids as proton ($H^+$) donors and bases as proton ($H^+$) acceptors, where acid-base transformations occur concertedly through protolysis.

Autoprotolysis of Water (Autoprotolyse)

The self-ionization equilibrium of pure water ($2H_2O \rightleftharpoons H_3O^+ + OH^-$) yielding an ion product at $25\,^\circ\text{C}$ of $c(H_3O^+) \times c(OH^-) = 10^{-14}\,mol^2\,dm^{-6}$, which establishes a neutral $pH$ of $7$.

Electronegativity (EN)

A dimensionless chemical measure of an atom's relative ability within a chemical bond to attract bonding electron pairs toward itself; a difference of $\Delta EN > 1.7$ indicates significant ionic bond character.

Mesomerism / Resonance (Mesomerie)

The concept wherein the genuine electronic structure of a molecule cannot be captured by a single static Lewis formula and is instead represented by multiple contributing boundary resonance structures (Grenzformeln) with delocalized electrons.

Formal Charge (Formalladung)

The fictitious charge allocated to an individual atom in a Lewis formula, calculated by the formula $N = N_A - N_B$, where $N_A$ represents the valence electrons of the isolated neutral atom and $N_B$ represents all unshared electrons plus half of all bonding electrons.

VSEPR / EPA Model (Gillespie-Nyholm-Modell)

Valence Shell Electron Pair Repulsion model asserting that mutually repulsive valence electron domains around a central atom maximize their spatial separation distance, establishing spatial molecular geometry.

Van der Waals Forces (vdW-Kräfte)

Relatively weak intermolecular forces (magnitude $\approx 2\,kJ\,mol^{-1}$) acting between nonpolar particles, arising from spontaneous, transient shifts in electron cloud density that induce complementary dipoles in neighboring atoms or molecules.

Lattice Energy (Gitterenergie)

The electrostatic potential energy released during the condensation of gaseous cations and anions into a solid crystalline salt lattice, or conversely the energy necessary to disassemble the lattice into separated gaseous ions.

Metallic Bonding (Metallbindung)

A chemical bonding mode between metal atoms in which valence electrons delocalize into a shared 'electron gas' that electrostatically binds closely packed, positively charged atomic cores (Atomrümpfe).

Ampholyte (Ampholyt)

A chemical compound or ion capable of reacting as both a Brønsted acid (proton donor) and a Brønsted base (proton acceptor) depending on reaction partners, exemplified by $H_2O$ and $HCO_3^-$.

Oxidation State (Oxidationszahl, OZ)

A formal integer assigned to an atom in a molecule or polyatomic ion, corresponding to the electrical charge the atom would bear if all bonding electron pairs were completely attributed to the more electronegative partner.

Reducing Agent (Reduktionsmittel)

A chemical species that donates electrons during a redox process, thereby causing the reduction of another reactant while its own central atom is oxidized and increases in oxidation state.

Pro analysi (p. a.)

A high laboratory chemical purity specification on reagent packaging designating that the chemical substance is manufactured and certified specifically for precise quantitative analytical procedures.

Purissimum (puriss.)

A chemical purity grade designating high-purity laboratory reagents with a certified principal component mass fraction content exceeding $99.0\%$.

Mass Fraction (Massenanteil, $w$)

A dimensionless concentration metric defined as the mass of a targeted component $m(x)$ divided by the total mass of the mixture or solution: $w(x) = \frac{m(x)}{m(\text{Gesamt})}$.

Water of Crystallization (Kristallwasser)

Water molecules bound stoichiometrically in defined ratios within the solid crystal lattice of an inorganic compound (such as $CoCl_2 \cdot 6H_2O$), which cannot be driven off through routine laboratory oven drying.

Mass Concentration (Massenkonzentration, $\beta$)

The ratio of the mass of a dissolved substance $m(x)$ to the total volume of the resulting solution $V(\text{Lösung})$, expressed as $\beta(x) = \frac{m(x)}{V(\text{Lösung})}$.

Molar Concentration (Stoffmengenkonzentration, $c$)

The chemical amount of substance in moles $n(x)$ per unit volume of solution $V(\text{Gesamt})$, represented as $c(x) = \frac{n(x)}{V(\text{Gesamt})}$ with SI-derived unit $mol\,dm^{-3}$.

Chemical Yield (Ausbeute, $\eta$)

The quantitative measure of reaction efficiency defined as the ratio of practically obtained product quantity to the theoretically calculated stoichiometric product quantity: $\eta = \frac{m(\text{praktisch})}{m(\text{theoretisch})} \times 100\%$.

Standard Molar Volume (Molares Gasvolumen)

The constant volume occupied by exactly $1\,mol$ of any ideal gas under standard temperature and pressure conditions ($T = 273.15\,K$, $p = 1.013\,bar$), equaling exactly $22.41\,dm^3\,mol^{-1}$.

Titer ($t$)

A dimensionless correction coefficient applied in quantitative volumetric titrations that relates the practical actual concentration $c$ of a volumetric standard solution to its approximate stated concentration $\tilde{c}$ via $c = \tilde{c} \times t$.

Primary Standard (Urtitersubstanz)

A highly pure, air-stable, non-hygroscopic reference chemical possessing an elevated molar mass, used to standardize volumetric titrant solutions by providing an indisputable reference mass.

Radioactive Decay Law

The exponential expression $N_t = N_0 \times e^{-\lambda \times t}$ describing nuclear decay, in which the characteristic decay constant $\lambda$ relates to the isotopic half-life $t_{1/2}$ via the relationship $\lambda = \frac{\ln(2)}{t_{1/2}}$.

Arithmetic Mean (Arithmetischer Mittelwert, $\bar{x}$)

A measure of central tendency calculated by dividing the sum of all observed values by the total number of observations $n$: $\bar{x} = \frac{\sum x_i}{n}$.

Standard Deviation (Standardabweichung, $s$)

A statistical metric measuring dispersion around the mean within an experimental sample, computed via the formula $s = \sqrt{\frac{\sum (x_i - \bar{x})^2}{n - 1}}$.

Coefficient of Variation (Variationskoeffizient, $s_{rel}$)

A normalized parameter of dispersion representing the sample standard deviation as a proportion or percentage of the arithmetic mean: $s_{rel} = v = \frac{s}{\bar{x}} \times 100\%$.

Specific Heat Capacity (Spezifische Wärmekapazität, $c$)

The quantity of thermal energy needed to alter the temperature of $1\,kg$ of a specific homogeneous substance by $1\,K$, governed by the caloric formula $Q = m \times c \times \Delta T$.

Specific Latent Heat (Spezifische Schmelz- und Verdampfungswärme, $q$)

The thermal energy transferred per unit mass during an isothermal phase transition (such as melting or vaporization) at constant temperature, calculated via $Q = m \times q$.

Saturated Vapor Pressure (Sättigungsdampfdruck)

The thermodynamic pressure exerted by a gas phase when in continuous dynamic equilibrium with its liquid phase within a closed system at a specified temperature.

Triple Point (Tripelpunkt)

The precise state in a phase diagram characterized by a unique temperature and pressure at which the solid, liquid, and gaseous phases of a pure substance coexist in thermodynamic equilibrium (for water: $0.01\,^\circ\text{C}$ and $\approx 6\,mbar$).

Critical Point (Kritischer Punkt)

The thermodynamic endpoint of the liquid-gas coexistence curve beyond which distinct phase boundaries vanish, creating a supercritical fluid (for water: $\approx 374\,^\circ\text{C}$ and $221\,bar$).

Raoult's Law (Raoultsches Gesetz)

A physical law stating that the vapor pressure of a solvent above an ideal solution equals the mole fraction of the solvent multiplied by the saturation vapor pressure of the pure solvent: $p = \chi(\text{Lösemittel}) \times p^0(\text{Lösemittel})$.

Eutectic Mixture (Eutektisches Gemisch)

A precise multicomponent solid-liquid mixture exhibiting an invariant, sharp melting point that is lower than the individual melting points of all constituent components.

Azeotrope (Azeotrop)

A liquid mixture of two or more compounds whose vapor possesses the identical composition as the boiling liquid, meaning it distills at a constant boiling temperature without composition changes.

Rectification (Rektifikation)

A fractional countercurrent distillation technique carried out in packed or plate columns, consisting of multiple sequential condensation and vaporization cycles through heat and mass transfer.

Theoretical Plate (Theoretischer Boden)

A theoretical equilibrium increment within a rectification column wherein ascending vapor and descending condensed liquid attain thermodynamic phase equilibrium.

Reflux Ratio (Rücklaufverhältnis)

The operational quotient in a column head defined as the volume of condensed distillate returned to the column to maintain fractionation relative to the volume permanently removed as top product.

Recrystallization (Umkristallisation)

A laboratory purification procedure for solid organic and inorganic compounds based on temperature-dependent solubility variations between a hot and a cold solvent.

Newton's First Law (Lex prima / Trägheitsprinzip)

The fundamental mechanical axiom stating that an object remains in a state of rest or uniform motion in a straight line unless acted upon by a non-zero external net force.

Newton's Second Law (Lex secunda / Aktionsprinzip)

The quantitative mechanical law expressing that the net force applied to an object equals the product of its mass and resultant acceleration: $F = m \times a$.

Newton's Third Law (Lex tertia / Reaktionsprinzip)

The principle of mechanical action and reaction stating that forces always occur in equal and opposite pairs: if body A exerts a force on body B, body B exerts an equal force in the opposite direction on body A.

Hydrostatic Paradox (Hydrostatisches Paradoxon)

The physical principle showing that the hydrostatic pressure ($p = \rho \times g \times h$) at the base of a resting liquid depends solely on liquid density and vertical depth, regardless of container geometry or liquid mass.

Barometric Formula (Barometrische Höhenformel)

The exponential mathematical formula $p(h) = p_0 \times e^{-\frac{\rho_0 \times g \times h}{p_0}}$ describing how atmospheric pressure decreases continuously with increasing elevation due to gas compressibility.

Wöhler Synthesis (1828)

The historical chemical transformation wherein Friedrich Wöhler converted the inorganic salt ammonium cyanate ($NH_4OCN$) into organic urea, disproving the vitalistic doctrine that organic matter requires a special vital force (vis vitalis).

Constitutional Isomerism (Konstitutionsisomerie)

A form of isomerism describing compounds that share identical empirical and molecular formulas but differ fundamentally in the structural sequence and connectivity of their atoms (comprising skeletal, positional, and functional isomers).

Radical Substitution ($S_R$)

A multistep reaction pathway characteristic of alkanes reacting with halogens under thermal or ultraviolet irradiation, advancing through initiation, radical chain propagation, and termination steps.

Alkane Halogenation Regioselectivity

The empirical regiochemical observation in radical substitution reactions that replacement occurs predominantly at the most highly substituted carbon atom (tertiary before secondary before primary), reflecting radical intermediate stability.

$E/Z$ Stereoisomerism (cis-trans-Isomerie)

Geometric stereoisomerism occurring across rigid double bonds lacking free rotation; assigned as $Z$ (zusammen) when priority substituents on both carbons reside on the same side, and $E$ (entgegen) when on opposite sides.

Markovnikov's Rule (Regel von Markownikow)

A rule stating that in the electrophilic addition of polar reagents ($HX$ or $H_2O$) to unsymmetrical alkenes, the hydrogen electrophile attaches to the carbon atom bearing more hydrogen substituents, forming the more stable carbocation intermediate.

Lindlar Catalyst (Lindlar-Katalysator)

A deactivated, poisoned palladium catalyst (treated with quinoline or lead acetate) that selectively stops the catalytic hydrogenation of alkynes at the cis-alkene stage, preventing over-reduction to alkanes.

Keto-Enol Tautomerism (Keto-Enol-Tautomerie)

An equilibrium structural isomerization involving the rapid, reversible intramolecular migration of a proton and double bond between an enol form and an aldehyde or ketone carbonyl form.

Saytzeff's Rule (Saytzeff-Regel)

A regiochemical rule governing base-induced 1,2-elimination reactions of haloalkanes, stating that the reaction preferentially generates the thermodynamically more stable, more highly alkyl-substituted alkene.

Grignard Reagent (Grignard-Reagenz)

An organomagnesium halide compound ($R\text{-}Mg\text{-}X$) synthesized from a haloalkane and magnesium in dry, peroxide-free ether, which functions as a strong carbon nucleophile capable of reacting with carbonyls to yield alcohols.

Williamson Ether Synthesis (Williamson'sche Ethersynthese)

An organic bimolecular substitution ($S_N2$) method that forms symmetrical or asymmetrical ethers through the nucleophilic reaction of an alkoxide anion ($R\text{-}O^-$) with an unhindered primary alkyl halide ($R'\text{-}X$).

Crown Ethers (Kronenether)

Macrocyclic polyethers containing multiple repeating ether oxygens oriented inward to chelate and solubilize alkali metal cations within an interior hydrophilic cavity while presenting an exterior lipophilic framework in organic solvents.