chemistry Flashcards
Define the periodic table.
Arrangement of elements by increasing atomic number, showing periodic trends.
Explain groups and periods on the periodic table.
Groups: vertical columns with similar properties; Periods: horizontal rows showing gradual changes in properties.
Define electronegativity.
Measure of an atom’s ability to attract electrons in a bond.
Explain ionization energy.
Energy required to remove an electron from an atom in the gaseous state.
Describe atomic radius and its trend.
Atomic radius is the size of an atom, which decreases across a period and increases down a group.
Define electron affinity.
Energy change when an atom gains an electron.
Describe metallic and nonmetallic character.
Metallic character increases down a group and decreases across a period; nonmetallic character shows the opposite trend.
Explain the properties of alkali metals.
Highly reactive, soft metals with one valence electron, found in Group 1.
Describe the halogens and their properties.
Reactive nonmetals in Group 17, with seven valence electrons, forming salts with metals.
Define noble gases and their characteristics.
Elements in Group 18; inert gases with full valence shells, very low reactivity.
Define chemical reaction.
Process where reactants convert into products with new chemical properties.
Describe the law of conservation of mass.
Mass is conserved in a chemical reaction; total mass of reactants equals total mass of products.
Define a mole and Avogadro’s number.
Mole: amount of substance containing 6.022 × 10^23 particles (Avogadro’s number).
Explain molar mass and how to calculate it.
Molar mass is the mass of one mole of a substance, calculated by summing atomic masses.
Define empirical and molecular formulas.
Empirical formula: simplest ratio of elements; Molecular formula: actual number of atoms in a molecule.
Explain the process of balancing chemical equations.
Ensure the same number of each atom on both sides of the equation.
Define limiting reactant.
The reactant that is completely used up, limiting the amount of product formed.
Explain percent yield and its formula.
Percent yield = (actual yield / theoretical yield) × 100.
Define exothermic and endothermic reactions.
Exothermic: releases energy; Endothermic: absorbs energy.
Describe activation energy.
Minimum energy required to initiate a chemical reaction.
Define acid and base according to Arrhenius.
Acid: produces H⁺ ions in water; Base: produces OH⁻ ions in water.
Define acid and base according to Bronsted-Lowry.
Acid: proton donor; Base: proton acceptor.
Describe the pH scale.
Scale from 0 to 14 measuring acidity/alkalinity; 7 is neutral, below 7 is acidic, above 7 is basic.
Explain the pH formula and how to calculate it.
pH = -log[H⁺], where [H⁺] is the concentration of hydrogen ions.
Define strong and weak acids.
Strong acids completely ionize in water; Weak acids partially ionize.
Explain neutralization reaction.
Reaction between an acid and a base, producing water and a salt.
Define buffer solution.
Solution that resists changes in pH when small amounts of acid/base are added.
Explain the role of conjugate acid-base pairs.
Conjugate pairs differ by one proton; acid donates a proton, base accepts it.
Describe titration and its purpose.
Technique to determine concentration of a solution using a known reactant.
Define the equivalence point in titration.
Point where moles of acid equal moles of base in a titration.
Define enthalpy (H).
Heat content of a system at constant pressure.
Explain Hess’s Law.
The enthalpy change of a reaction is the same, regardless of the reaction pathway.
Define standard enthalpy change of formation.
Enthalpy change when 1 mole of a compound is formed from its elements in standard states.
Describe endothermic and exothermic reactions in terms of enthalpy.
Endothermic: positive enthalpy change; Exothermic: negative enthalpy change.
Explain activation energy in kinetics.
Minimum energy required for a reaction to occur.
Define catalyst and its effect on reaction rate.
Catalyst speeds up a reaction without being consumed, by lowering activation energy.
Describe the collision theory of reactions.
For a reaction to occur, particles must collide with sufficient energy and proper orientation.
Explain rate of reaction and how it’s measured.
Change in concentration of reactants/products per unit time; measured by change in mass, volume, or color.
Define reaction mechanism.
Series of steps that show the pathway from reactants to products.
Explain Le Chatelier’s Principle.
If a dynamic equilibrium is disturbed, the system shifts to counteract the disturbance.
Define organic chemistry.
Study of carbon-containing compounds and their reactions.
Describe alkanes and give an example.
Saturated hydrocarbons with single bonds; Example: methane (CH₄).
Define alkenes and their general formula.
Unsaturated hydrocarbons with double bonds; Formula: CₙH₂ₙ.
Describe alkynes and their general formula.
Unsaturated hydrocarbons with triple bonds; Formula: CₙH₂ₙ₋₂.
Define functional group and give examples.
Specific groups of atoms that determine properties of organic molecules; Examples: -OH, -COOH.
Describe alcohols and their general formula.
Organic compounds with -OH group; General formula: CₙH₂ₙ₊₁OH.
Define carboxylic acids and their properties.
Organic acids with -COOH group; weakly acidic with sour taste.
Describe esters and their formation.
Formed by reaction between acids and alcohols, used in fragrances and flavors.
Explain isomers and types of isomerism.
Compounds with the same molecular formula but different structures; Types: structural and stereoisomerism.
Describe polymers and give examples.
Large molecules made of repeating units; Examples: polyethylene, proteins.
Define chemical equilibrium.
State where forward and reverse reaction rates are equal, and concentrations remain constant.
Describe equilibrium constant (Kc).
Ratio of product to reactant concentrations at equilibrium, specific to a reaction at a given temperature.
Explain the effect of temperature on equilibrium.
Increasing temperature favors endothermic reactions, while decreasing temperature favors exothermic reactions.
Define redox reaction.
Reaction involving transfer of electrons, with oxidation and reduction occurring simultaneously.
Explain oxidation and reduction.
Oxidation: loss of electrons; Reduction: gain of electrons.
Describe the role of an oxidizing agent.
Substance that gains electrons and is reduced in a redox reaction.
Define electrochemical cell and its components.
Device generating electricity from a redox reaction, with electrodes and electrolyte.
Explain standard electrode potential (E°).
Measure of the tendency of a half-cell to gain or lose electrons under standard conditions.
Describe the function of a salt bridge in a galvanic cell.
Maintains electrical neutrality by allowing ion flow between half-cells.
Explain Faraday’s laws of electrolysis.
First law: mass of substance deposited is proportional to charge; Second law: mass deposited is proportional to molar mass.
