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🧪AP Chemistry Unit 4 Vocabulary

63 essential vocabulary terms and definitions for Unit 4 – Chemical Reactions

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🧪Unit 4 – Chemical Reactions
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🧪Unit 4 – Chemical Reactions

4.1 Introduction for Reactions

TermDefinition
chemical changeA process in which substances are rearranged into new combinations, resulting in the formation of new substances with different properties.
mixtureMaterials that contain atoms, molecules, or formula units of two or more types, whose relative proportions can vary.
phaseA distinct state of matter: solid, liquid, or gas.
physical changeA change in matter that does not alter the chemical composition or identity of the substance.
precipitateA solid substance that forms and separates from a solution during a chemical reaction.

4.2 Net Ionic Equations

TermDefinition
balanced chemical equationA chemical equation where the number of atoms of each element is equal on both the reactant and product sides.
chemical changeA process in which substances are rearranged into new combinations, resulting in the formation of new substances with different properties.
complete ionic equationA balanced equation that shows all ions and molecules present in solution, including spectator ions.
conservation of chargeThe principle that the total electric charge is neither created nor destroyed in a chemical reaction; total charge is equal on both sides of the equation.
conservation of massThe principle that mass is neither created nor destroyed in a chemical reaction; the total mass of reactants equals the total mass of products.
molecular equationA balanced chemical equation that represents all reactants and products in their molecular form.
net ionic equationA symbolic representation of a chemical reaction that shows only the ions and molecules that actually participate in the reaction, excluding spectator ions.
physical changeA change in matter that does not alter the chemical composition or identity of the substance.

4.3 Representations of Reactions

TermDefinition
balanced chemical equationA chemical equation where the number of atoms of each element is equal on both the reactant and product sides.
chemical reactionA process in which substances are transformed into different substances through the breaking and forming of chemical bonds.
particulate modelA representation of matter showing individual atoms, molecules, or ions and their interactions to describe chemical processes at the molecular level.
physical processA change in the state or properties of matter that does not alter the identity of the substances involved.
symbolic representationA depiction of chemical reactions using chemical formulas, symbols, and equations to represent reactants and products.

4.4 Physical and Chemical Changes

TermDefinition
bond interactionsThe forces between atoms or molecules, including chemical bonds and intermolecular forces, that determine the properties and behavior of substances.
chemical processA transformation in which substances are converted into different substances through the breaking and forming of chemical bonds.
dissolutionThe process by which a solute dissolves in a solvent to form a solution, involving the breaking of bonds or interactions in the solute and formation of new interactions with the solvent.
intermolecular interactionsForces between molecules, such as hydrogen bonding, dipole-dipole forces, and London dispersion forces, that affect the physical and chemical properties of substances.
ion-dipole interactionsAttractive forces between an ion and a polar molecule, where the charged ion interacts with the partial charges on the polar molecule.
ionic bondsChemical bonds formed between positively and negatively charged ions through electrostatic attraction.
macroscopic characteristicsObservable properties of matter that can be seen and measured without a microscope, such as color, state, temperature, and solubility.
phase transitionThe process by which a substance changes from one state of matter to another (solid, liquid, or gas).
physical processA change in the state or properties of matter that does not alter the identity of the substances involved.

4.5 Stoichiometry

TermDefinition
atom conservationThe principle that atoms cannot be created, destroyed, or changed during a chemical process, so the total number and type of atoms remain constant.
balanced chemical equationA chemical equation where the number of atoms of each element is equal on both the reactant and product sides.
coefficientsThe numbers placed in front of chemical formulas in a balanced equation that indicate the relative proportions of reactants and products involved in the reaction.
ideal gas lawThe equation PV = nRT that relates pressure, volume, number of moles, and temperature of an ideal gas.
molarityA measure of solution concentration expressed as the number of moles of solute dissolved per liter of solution.
mole conceptA fundamental chemistry concept that relates the number of particles (atoms, molecules, or ions) to measurable quantities through Avogadro's number.
productSubstances formed as a result of a chemical reaction.
reactantSubstances that are consumed in a chemical reaction to form products.
stoichiometric calculationsQuantitative calculations using balanced chemical equations and mole ratios to determine amounts of reactants consumed or products formed in a chemical reaction.

4.6 Introduction to Titration

TermDefinition
analyteThe substance in a solution whose amount or concentration is being determined during a titration.
endpointThe observable event or change in property (such as color) that indicates when the equivalence point has been reached in a titration.
equivalence pointThe point in a titration where the analyte is completely consumed by the titrant in a quantitative reaction.
titrantA solution of known concentration that is added to an analyte during a titration to determine the amount of analyte present.
titrationAn analytical procedure used to determine the amount of an analyte in solution by reacting it with a titrant of known concentration.

4.7 Types of Chemical Reactions

TermDefinition
acid-base reactionA chemical reaction involving the transfer of one or more protons (H⁺ ions) between chemical species.
aqueous solutionA solution in which water is the solvent.
combustionA type of oxidation-reduction reaction in which a species reacts with oxygen gas to produce products such as carbon dioxide and water.
electron transferThe movement of one or more electrons from one chemical species to another in a redox reaction.
hydrocarbonsOrganic compounds composed of carbon and hydrogen atoms that undergo complete combustion to produce carbon dioxide and water.
insolubleUnable to dissolve in a solvent, such as water; describes compounds that form as precipitates.
ionic compoundCompounds formed by the electrostatic attraction between positively charged cations and negatively charged anions.
oxidation numbersNumbers assigned to atoms in reactants and products to track electron transfer and identify oxidized and reduced species in a redox reaction.
oxidation-reduction reactionA chemical reaction involving the transfer of one or more electrons between chemical species, indicated by changes in oxidation numbers.
oxidizedThe process in which a species loses electrons in a redox reaction.
precipitation reactionA chemical reaction in which ions in aqueous solution combine to produce an insoluble or sparingly soluble ionic compound.
proton transferThe movement of a proton (H⁺) from one species to another in an acid-base reaction.
reducedThe process in which a species gains electrons in a redox reaction.
sparingly solubleSlightly soluble in a solvent; describes ionic compounds that form precipitates when ions combine in aqueous solution.

4.8 Introduction to Acid-Base Reactions

TermDefinition
aqueous solutionA solution in which water is the solvent.
Brønsted-Lowry acidA species that donates a proton (H⁺) in a chemical reaction.
Brønsted-Lowry baseA species that accepts a proton (H⁺) in a chemical reaction.
conjugate acid-base pairTwo species that differ by one proton, where one is the acid form and the other is the base form of the same substance.
ionizationThe process by which an acid or base separates into ions when dissolved in water.
proton transferThe movement of a proton (H⁺) from one species to another in an acid-base reaction.

4.9 Oxidation-Reduction (Redox) Reactions

TermDefinition
balanced redox reaction equationA chemical equation for an oxidation-reduction reaction where the number of electrons lost equals the number of electrons gained, and all atoms and charges are balanced.
half-reactionSeparate equations showing either the oxidation process (loss of electrons) or the reduction process (gain of electrons) in a redox reaction.