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# Chemistry ## Properties of Matter ### States of Matter * **Solid:** Definite shape and volume * **Liquid:** Definite volume, takes shape of container * **Gas:** No definite shape or volume * **Plasma:** Ionized gas, high temperature ### Phase Changes * Solid to Liquid: Melting (Endo...

# Chemistry ## Properties of Matter ### States of Matter * **Solid:** Definite shape and volume * **Liquid:** Definite volume, takes shape of container * **Gas:** No definite shape or volume * **Plasma:** Ionized gas, high temperature ### Phase Changes * Solid to Liquid: Melting (Endothermic) * Liquid to Solid: Freezing (Exothermic) * Liquid to Gas: Vaporization (Endothermic) * Gas to Liquid: Condensation (Exothermic) * Solid to Gas: Sublimation (Endothermic) * Gas to Solid: Deposition (Exothermic) ### Chemical vs. Physical Properties * **Physical:** Observed without changing composition (e.g., boiling point, density) * **Chemical:** Ability to undergo chemical change (e.g., flammability, reactivity) ### Intensive vs. Extensive Properties * **Intensive:** Independent of amount (e.g., temperature, pressure) * **Extensive:** Depends on amount (e.g., mass, volume) ## Atomic Structure ### Subatomic Particles * **Protons:** Located in the nucleus, positive charge, mass ≈ 1 amu * **Neutrons:** Located in the nucleus, no charge, mass ≈ 1 amu * **Electrons:** Orbit the nucleus, negative charge, negligible mass ### Atomic Number (Z) * Number of protons in the nucleus * Determines the element ### Mass Number (A) * Number of protons + number of neutrons in the nucleus * Isotopes: Atoms with the same number of protons but different numbers of neutrons ### Ions * **Cation:** Positive ion, formed by losing electrons * **Anion:** Negative ion, formed by gaining electrons ## The Mole ### Avogadro's Number * $N_A = 6.022 \times 10^{23}$ entities/mole * Converts between moles and number of entities ### Molar Mass (MM) * Mass of one mole of a substance (g/mol) * Numerically equal to the atomic or molecular weight ### Conversions * Moles = Mass / Molar Mass * Mass = Moles x Molar Mass ## Chemical Reactions ### Balancing Equations * Law of Conservation of Mass: Matter cannot be created or destroyed * Balancing ensures the same number of atoms of each element on both sides ### Stoichiometry * Using balanced equations to determine relationships between reactants and products * Mole ratios: Coefficients in the balanced equation represent mole ratios ### Limiting Reactant * Reactant that is completely consumed in a reaction * Determines the amount of product formed ### Percent Yield * Actual Yield / Theoretical Yield x 100% ## Solutions ### Concentration * Molarity (M) = Moles of Solute / Liters of Solution * Molality (m) = Moles of Solute / Kilograms of Solvent ### Dilution * $M_1V_1 = M_2V_2$ ### Solubility * "Like dissolves Like" (Polar dissolves polar, nonpolar dissolves nonpolar) * Factors affecting solubility: Temperature, pressure (for gases) ## Acids and Bases ### Definitions * **Arrhenius:** Acid produces $H^+$ in water, base produces $OH^-$ in water * **Bronsted-Lowry:** Acid is a proton ($H^+$) donor, base is a proton acceptor * **Lewis:** Acid is an electron pair acceptor, base is an electron pair donor ### pH Scale * $pH = -log[H^+]$ * $pOH = -log[OH^-]$ * $pH + pOH = 14$ ### Strong Acids and Bases * **Strong Acids:** Completely dissociate in water (e.g., HCl, $H_2SO_4$) * **Strong Bases:** Completely dissociate in water (e.g., NaOH, KOH) ### Titration * Using a known concentration of acid or base to determine the concentration of an unknown * Equivalence point: Moles of acid = Moles of base ## Gases ### Ideal Gas Law * $PV = nRT$ * P = Pressure * V = Volume * n = Number of moles * R = Ideal gas constant (0.0821 L atm / (mol K) or 8.314 J / (mol K)) * T = Temperature (in Kelvin) ### Gas Laws * Boyle's Law: $P_1V_1 = P_2V_2$ (constant T, n) * Charles's Law: $\frac{V_1}{T_1} = \frac{V_2}{T_2}$ (constant P, n) * Avogadro's Law: $\frac{V_1}{n_1} = \frac{V_2}{n_2}$ (constant T, P) ### Dalton's Law of Partial Pressures * $P_{total} = P_1 + P_2 + P_3 +...$ ## Thermodynamics ### Laws of Thermodynamics * **1st Law:** Energy is conserved: $\Delta U = Q - W$ * **2nd Law:** Entropy of an isolated system increases: $\Delta S > 0$ ### Enthalpy ($\Delta H$) * Measure of heat change at constant pressure * $\Delta H < 0$: Exothermic (heat released) * $\Delta H > 0$: Endothermic (heat absorbed) ### Entropy ($\Delta S$) * Measure of disorder or randomness * $\Delta S > 0$: Increase in disorder * $\Delta S < 0$: Decrease in disorder ### Gibbs Free Energy ($\Delta G$) * Determines spontaneity of a reaction * $\Delta G = \Delta H - T\Delta S$ * $\Delta G < 0$: Spontaneous * $\Delta G > 0$: Non-spontaneous * $\Delta G = 0$: Equilibrium ## Kinetics ### Rate Laws * Rate = $k[A]^m[B]^n$ * k = Rate constant * [A], [B] = Concentrations of reactants * m, n = Reaction orders * Overall reaction order = m + n ### Reaction Order * 0th order: Rate is independent of concentration * 1st order: Rate is directly proportional to concentration * 2nd order: Rate is proportional to the square of concentration ### Activation Energy ($E_a$) * Minimum energy required for a reaction to occur * Catalysts: Lower the activation energy ## Equilibrium ### Equilibrium Constant (K) * $aA + bB \rightleftharpoons cC + dD$ * $K = \frac{[C]^c[D]^d}{[A]^a[B]^b}$ * K > 1: Products favored * K < 1: Reactants favored ### Le Chatelier's Principle * If a stress is applied to a system at equilibrium, the system will shift to relieve the stress * Stressors: Change in concentration, pressure, temperature ## Redox Reactions ### Oxidation and Reduction * **Oxidation:** Loss of electrons (increase in oxidation number) * **Reduction:** Gain of electrons (decrease in oxidation number) ### Oxidizing and Reducing Agents * **Oxidizing Agent:** Accepts electrons (is reduced) * **Reducing Agent:** Donates electrons (is oxidized) ### Balancing Redox Reactions * Half-reaction method: Separate into oxidation and reduction half-reactions, balance atoms and charges, combine half-reactions ## Nuclear Chemistry ### Radioactive Decay * Alpha decay: Emission of an alpha particle ($^4_2He$) * Beta decay: Emission of a beta particle ($^0_{-1}e$) * Gamma decay: Emission of a gamma ray ($\gamma$) ### Half-Life * Time required for half of the radioactive nuclei to decay * $N(t) = N_0 e^{-\lambda t}$ * $N(t)$ = Amount at time t * $N_0$ = Initial amount * $\lambda$ = Decay constant * t = time ## Organic Chemistry ### Functional Groups * Alkanes, Alkenes, Alkynes, Alcohols, Ethers, Aldehydes, Ketones, Carboxylic Acids, Amines, Amides * Nomenclature: IUPAC naming conventions ### Isomers * Structural isomers: Different connectivity * Stereoisomers: Same connectivity, different spatial arrangement (e.g., cis/trans, enantiomers) This document provides a comprehensive overview of key concepts in chemistry, including properties of matter, atomic structure, the mole, chemical reactions, solutions, acids and bases, gases, thermodynamics, kinetics, equilibrium, redox reactions, nuclear chemistry, and organic chemistry. It covers definitions, formulas, and principles essential for understanding chemical processes and phenomena.