Chem final

Energy

The capacity to do work or transfer heat.

Kinetic Energy

Energy associated with an object's motion.

Potential Energy

Energy related to an object's position.

Joule (J)

The SI unit of energy.

Calorie (cal)

The amount of energy needed to raise the temperature of 1 g of water by 1°C.

Work (w)

The energy resulting from a force acting on an object over a distance.

Heat (q)

The flow of energy that causes a temperature change in an object or its surroundings.

First Law of Thermodynamics

States that energy cannot be created or destroyed, only transferred or converted.

Internal Energy (U)

The sum of all kinetic and potential energies of the particles in a system.

Enthalpy (H)

A state function that relates internal energy, pressure, and volume.

Calorimetry

The study of heat transfers by measuring temperature changes.

Bond Enthalpy

The enthalpy change associated with breaking a bond in 1 mol of gaseous molecules.

State Function

A property that depends only on the state of a system, not on the path taken to achieve that state.

Path Function

A value that depends on the sequence of steps taken to achieve a certain state.

Specific Heat (c)

The amount of heat required to raise the temperature of a substance by 1°C.

Lattice Energy

The energy released when gas-phase ions are converted into a solid ionic compound.

Standard Enthalpy of Formation

The enthalpy change when 1 mol of a compound is formed from its elements in their standard states.

Hess's Law

States that the total enthalpy change for a reaction is the sum of the enthalpy changes for individual steps.

Chemical Equation

A symbolic representation of a chemical reaction where reactants are transformed into products.

Reactants

Substances that undergo change in a chemical reaction.

Products

Substances formed as a result of a chemical reaction.

Balanced Equation

An equation with equal numbers of each type of atom on both sides.

Coefficients

Numbers placed before compounds in a chemical equation to indicate the number of molecules involved.

Physical States

Designations in a chemical equation (solid - s, liquid - l, gas - g, aqueous - aq) indicating the state of each reactant or product.

Precipitation Reaction

A type of reaction where soluble ionic compounds react in solution to form an insoluble compound.

Acid-Base Reaction

A type of reaction that involves an acid reacting with a base to produce water and a salt.

Redox Reactions

Reactions that involve the transfer of electrons, encompassing oxidation and reduction.

Oxidation State

A number assigned to an element in a compound that reflects the number of electrons lost or gained.

Electrolyte

A substance that, when dissolved in water, conducts electricity due to the presence of ions.

Strong Acid

An acid that completely dissociates in solution to produce H+ ions.

Weak Acid

An acid that partially dissociates in solution, resulting in a lower concentration of H+ ions.

Combustion Reaction

A reaction that occurs when a substance reacts rapidly with oxygen, producing heat and light.

Dissociation

The process by which an ionic compound separates into ions when dissolved in water.

Net Ionic Equation

An equation that shows only the particles that participate in the reaction, excluding spectator ions.

Spectator Ion

Ions that do not participate in a reaction and remain unchanged.

VSEPR

Valence Shell Electron Pair Repulsion; a model used to predict the 3D shape of molecules based on electron pair repulsion.

Molecular Geometry

The three-dimensional arrangement of the atoms in a molecule.

Bond Angle

The angle formed between three atoms across at least two bonds.

Electron Domain

Regions in which electrons are likely to be found, including bonded atoms and lone pairs.

Trigonal Planar

Molecular shape with three electron domains arranged in a flat triangle.

Tetrahedral

Molecular shape with four electron domains forming a three-dimensional structure.

Polarity

A property of molecules that leads to a separation of electric charge, resulting in a dipole moment.

Sigma Bond (σ bond)

A type of covalent bond formed by the head-on overlap of atomic orbitals.

Pi Bond (π bond)

A type of covalent bond formed by the side-to-side overlap of atomic orbitals.

Hybridization

The mixing of atomic orbitals to form new hybrid orbitals suitable for pairing electrons to form chemical bonds.

Molecular Orbital Theory

A theory that accounts for the electronic structure of molecules by considering the collective behavior of electrons in molecular orbitals.

Antibonding Orbital

A molecular orbital that is higher in energy than any of the atomic orbitals that combine to form it, resulting in weaker bonding.

Resonance

The phenomenon where a molecule can be represented by multiple valid Lewis structures.

Paramagnetism

A tendency for a material to be attracted into a magnetic field, occurring in materials with unpaired electrons.

Diamagnetism

A tendency for a material to be repelled from a magnetic field, occurring in materials with all paired electrons.

Ionic Bonding

A type of bonding characterized by the transfer of electrons from one atom to another, resulting in the formation of oppositely charged ions.

Covalent Bonding

A type of bonding where atoms share pairs of electrons to achieve stable configurations.

Lewis Structures

Diagrams that show the bonding between atoms of a molecule and the lone pairs of electrons that may exist.

Octet Rule

The principle that atoms tend to bond in a way that gives them eight valence electrons, resulting in a stable electron configuration.

Electrostatic Attraction

The force of attraction between oppositely charged ions that helps to form ionic bonds.

Ionic Lattice

A three-dimensional arrangement of ions in a crystal structure, held together by ionic bonds.

Formal Charge

A theoretical charge assigned to an atom in a molecule, calculated by comparing the number of valence electrons with the electrons assigned to the atom in a Lewis structure.

Polar Bonds

Covalent bonds in which the electrons are shared unequally between the bonded atoms, resulting in partial charges.

Resonance Structures

Structures that represent a molecule or ion when a single Lewis structure is inadequate to describe it.

Dipole Moment

A quantity that measures the separation of positive and negative charges in a polar bond.

Radicals

Molecules that contain unpaired electrons, which are typically very reactive.

Expanded Octet

A situation in which an atom in the third period or beyond can accommodate more than eight electrons.

Bonding Continuum

The range of characteristics observed in bonds from nonpolar to ionic, depending on the differences in electronegativity.

Noble Gas Configuration

The electron configuration of a noble gas, which is often the goal when atoms form ionic or covalent bonds.

Electronegativity

A measure of an atom's ability to attract shared electrons in a bond.

Lone Pair Electrons

Valence electrons that are not involved in bonding and are localized on one atom.

Duet Rule

The principle that hydrogen and helium atoms are stable with two electrons in their outer shell.

Matter

Anything that has mass and occupies space.

Element

The simplest form of matter with distinct physical and chemical properties that cannot be broken down chemically.

Compound

A chemical combination of elements that has its own set of properties and a definite composition.

Pure Substance

A material with a definite composition that can be either an element or a compound.

Mixture

A physical combination of two or more pure substances that are not chemically bonded.

Homogeneous Mixture (Solution)

A mixture that is uniform in composition and the components are evenly distributed.

Heterogeneous Mixture

A mixture in which the composition is not uniform throughout.

Significant Digits

The digits in a measurement that carry meaningful information about its precision.

Density

A measure of mass per unit volume, often expressed in g/mL or kg/m³.

Scientific Method

A systematic process involving observation, hypothesis formulation, experimentation, and revision based on results.

Hypothesis

An initial explanation for an observed phenomenon that can be tested.

Theory

A widely accepted explanation of phenomena based on experimental evidence and observations.

Law

A statement that describes a phenomenon that always occurs under certain conditions, without explanation.

Temperature Scale

A system of measuring temperature, commonly Fahrenheit, Celsius, or Kelvin.

Dimensional Analysis

A mathematical technique used to convert units and solve problems using the units of measurements.

Physical Property

Characteristics of a substance that can be observed without changing its chemical composition.

Chemical Property

The ability of a substance to undergo a chemical change.

Molar Mass

The mass in grams of one mole of a substance.

Percent Composition

The percent by mass of each element in a compound.

Empirical Formula

The formula that gives the simplest whole-number ratio of atoms in a compound.

Molecular Formula

The formula that gives the actual number of atoms of each element in a molecule of a compound.

Combustion Analysis

A technique used to determine the empirical formula of a compound by measuring the amounts of CO2 and H2O produced.

Atomic Mass Unit (u)

A unit of mass used to express atomic and molecular weights.

Conversion Factor

A ratio used to convert between different units.

Allotropes

Different structural forms of the same element.

Stoichiometry

The branch of chemistry that deals with the calculation of reactants and products in chemical reactions.

Avogadro's Number

The number of particles (atoms or molecules) in one mole of a substance, approximately 6.022 x 10^23.

Hydrate

A compound that contains water molecules within its structure.

Formula Mass

The sum of the atomic masses of all atoms in a formula unit of a substance, expressed in atomic mass units (u).

Molar Mass (g/mol)

The numerical value of a substance's molar mass expressed in grams per mole.

Sublimation

The transition of a substance directly from the solid to the gas phase without passing through the liquid phase.

Atomic Mass

The weighted average mass of an element's isotopes compared to a standard.

Chemical Analysis

Techniques used to identify the composition of a chemical substance.