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Chemistry

Term	Definition
Atom	Fundamental building blocks of ordinary matter
Molecule	Two or more atoms joined together by chemical bonds
Chemistry	Study of matter
Hypothesis	Interpretation or explanation of observed phenomena
Experiment	Procedure intended to confirm or refute a hypothesis
Scientific Law	Brief statement that summarizes observations and predicts future phenomena
Scientific Theory	Model and explanation for natural occurrences and phenomena
Law of Conservation of Mass	Matter is neither created nor destroyed during a chemical reaction
Atomic Theory	Theory that matter is composed of small and indestructible particles called atoms
Matter	Anything that occupies space and has mass
Substance	Any specific instance of matter
State	Physical form of matter
Composition	Chemical makeup of matter
Solid	State of matter with a definite shape and volume; particles are packed close to one another
Liquid	State of matter with a definite volume but no definite shape; particles are free to move relative to each other
Gas	State of matter with no definite shape or volume; particles will fill the container that the substance is in
Pure Substance	Substance made of only one component
Mixture	Substance made of two or more components
Heterogenous Mixture	Mixture in which the composition varies from one region of the mixture to another
Homogenous Mixture	Mixture in which the composition is the same throughout
Element	Substance that cannot be chemically broken down into simpler substances
Compound	Substance composed of two or more elements
Decanting	Method of separating immiscible liquids by pouring the top layer into another container
Distillation	Process by which a mixture is heated to boil off the more volatile liquid
Filtration	Process by which a mixture composed of an insoluble solid and a liquid are separated by pouring the mixture through filter paper or some other porous membrane or layer
Physical Change	Change that only alters the state or appearance, not the composition, of matter
Chemical Change	Change that alters the chemical composition of matter
Physical Property	Property that a substance displays without changing its composition
Chemical Property	Property that a substance displays only by changing its chemical composition
Units	Standard Quantities used to specify measurements
International System of Units (SI Units)	Standard unit system used by scientists.
Mass	Quantity of matter within an object
Temperature	Measure of the average kinetic energy of the atoms or molecules that compose matter
Fahrenheit Scale	Temperature scale where water freezes at 32° and boils at 212°
Celsius Scale	Temperature scale where water freezes at 0° and boils at 100°
Kelvin Scale	Temperature scale where zero is the coldest temperature possible
Absolute Zero	Temperature at which molecular motion virtually stops; 0 Kelvin
Meter (m)	SI unit of length
Kilogram (kg)	SI unit of mass
Second (s)	SI unit of time
Kelvin (K)	SI unit of temperature
Mole (mol)	SI unit of amount of substance
Ampere (A)	SI unit of electric current
Candela (cd)	SI unit of luminous intensity
Exa (E)	Prefix multiplier equal to 10^18
Peta (P)	Prefix multiplier equal to 10^15
Tera (T)	Prefix multiplier equal to 10^12
Giga (G)	Prefix multiplier equal to 10^9
Mega (M)	Prefix multiplier equal to 10^6
Kilo (k)	Prefix multiplier equal to 10^3
Hecto (h)	Prefix multiplier equal to 10^2
Deca (da)	Prefix multiplier equal to 10^1
Deci (d)	Prefix multiplier equal to 10^-1
Centi (c)	Prefix multiplier equal to 10^-2
Milli (m)	Prefix multiplier equal to 10^-3
Micro (µ)	Prefix multiplier equal to 10^-6
Nano (n)	Prefix multiplier equal to 10^-9
Pico (p)	Prefix multiplier equal to 10^-12
Femto (f)	Prefix multiplier equal to 10^-15
Atto (a)	Prefix multiplier equal to 10^-18
Derived Unit	Combination of base units
Volume	Measure of space. Equal to any unit of length cubed
Liter (L)	Common unit of volume equal to one thousand milliliters
Density (d)	Ratio of a substance's mass to its volume
Intensive Property	Property that is independent of the amount of a substance
Extensive Property	Property that is dependent on the amount of a substance
Significant Figures	Non-placeholding digits that indicate the precision of a measured quantity
Exact Numbers	Numbers with no uncertainty. They do not limit the number of significant figures in a calculation
Accuracy	How close a measured value is to the actual value
Precision	How close a series of measurements are to one another
Random Error	Error that has equal probability of being too high or too low
Systematic Error	Error that tends to be consistently either too high or too low
Conversion Factor	Ratio used to convert from one unit to another
Dimensional Analysis	Use of units and conversion factors in calculations
Brownian Motion	Random motion of particles suspended in a liquid or gas
Law of Definite Proportions	All samples of a given compound have the same proportions of constituent elements
Law of Multiple Proportions	When two elements form two different compounds, the masses of the first element that combine with one gram of the second element can be expressed as a ratio of small whole numbers
Electric Charge	Tendency of certain particles to experience a force in the presence of electric fields
Proton	Positively charged particle found in the nucleus. It has the same mass as the neutron
Neutron	Neutrally charged particle found in the nucleus. It has the same mass as the proton
Electron	Negatively charged, low-mass particle present in all atoms. Orbits the nucleus
JJ Thomson	English physicist who discovered the electon
Robert Millikan	American physicist who deduced the electron's charge
Cathode Ray	Stream of electrons produced when a high electrical voltage is applied between two electrodes within a partially evacuated tube
Nucleus	Very small, dense core of an atom. It contains protons and neutrons
Atomic Mass Unit (amu)	Unit used to express the masses of atoms and subatomic particles. It is defined as one-twelfth of the mass of a carbon atom containing six protons and six neutrons (carbon-twelve)
Atomic Number	Number of protons in an atom's nucleus. Denoted by the letter Z
Chemical Symbol	One or two letter abbreviation for a chemical element
Isotopes	Atoms with the same number of protons but different numbers of electrons
Natural Abundance	Relative percentage of a particular isotope in a naturally occurring sample with respect to other isotopes
Mass Number	Sum of the number of neutrons and protons in an atom. Denoted by the symbol A
Ion	Atom or molecule with a net charge. Caused by the gain or loss of electrons
Cation	Ion with a positive net charge
Anion	Ion with a negative net charge
Periodic Law	Arranging elements in order of increasing mass produces recurring sets of certain properties
Metals	Elements that are good conductors, malleable, ductile, lustrous, and tend to lose electrons during reactions
Nonmetals	Elements that are poor conductors and tend to gain electrons during reactions
Metalloids	Elements that are found on the border of metals and nonmetals, and exhibit intermediate properties
Main-Group Elements	Elements in the 's' or 'p' blocks. They have easily predictable properties
Transition Elements	Elements in the 'd' block. Their properties are less predictable
Family (Group)	Column of the periodic table
Period	Row of the periodic table
Alkali Metals	Group 1A elements. They are highly reactive (Lithium, Potassium, Sodium, etc.)
Alkaline Earth Metals	Group 2A elements. They are fairly reactive (Calcium, Beryllium, Magnesium, etc.)
Boron Group	Group 3A elements. They have three valence electrons (Boron, Aluminum, Indium, etc.)
Carbon Group	Group 4A elements. They are also known as crystallogens (Carbon, Silicon, Tin, Lead, etc.)
Pnictogens	Group 5A elements. This group is also called the nitrogen family (Nitrogen, Phosphorus, Arsenic, etc.)
Chalcogens	Group 6A elements. This group is also called the oxygen family (Oxygen, Sulfur, Selenium, etc.)
Halogens	Group 7A elements. They react with metals to form salts (Fluorine, Chlorine, Iodine, etc.)
Noble Gases	Group 8A elements. They are very unreactive, or inert (Neon, Argon, Krypton, etc.)
Atomic Mass (Atomic Weight)	Average mass - in amu - of a particular element based on the relative abundance of the various isotopes. Numerically equivalent to the mass in grams of one mole of the element
Mass Spectrometry	Technique that separates particles by their mass. It is used in determining the precise masses and relative abundance of isotopes in a given sample
Avogadro's Number	6.022 × 10^23 particles; number of particles in one mole
Molar Mass	Mass of one mole of atoms of an element. Equal to the atomic mass in atomic mass units
Chemical Formula	Symbolic representation of a compound, indicating the elements present in the compound and the relative number of atoms of each element
Empirical Formula	Chemical formula that gives the relative number of atoms of each element in a compound
Molecular Formula	Chemical formula that gives the actual number of atoms of each element in a compound
Structural Formula	Chemical formula that uses lines to represent chemical bonds
Ball-and-Stick Model	Molecular model that represents atoms as ball and chemical bonds as sticks
Space-Filling Model	Molecular model where atoms fill the space between each other and are scaled by size
Atomic Elements	Elements that exist in nature with single atoms as their basic units
Molecular Elements	Elements that exist in nature with molecules as their basic units
Diatomic Molecules	Molecules composed of two atoms
Polyatomic Molecules	Molecules composed of three or more atoms
Formula Unit	Smallest, electrically neutral collection of ions in an ionic compound, such as NaCl for table salt
Polyatomic Ion	Ion composed of two or more atoms
Common Names	Nicknames for compounds that give little to not information about the chemical structure of the compound
Systematic Names	Official names for compounds that describe the chemical composition
Binary Compounds	Compounds that contain only two different elements
Oxyanions	Anions containing oxygen and another element
Hydrates	Ionic compounds containing a specific number of water molecules for each formula unit
Formula Mass	Average mass of a molecule in a compound. Synonymous with molecular mass and atomic mass
Mass Percent Composition	Element's percentage of the total mass of a compound containing the element
Combustion Analysis	Method for obtaining empirical formulas for unknown compounds, especially those containing carbon and hydrogen, by burning a sample of the compound in pure oxygen and analyzing the products
Chemical Reaction	Process in which one or more substances are converted into one or more different ones
Chemical Equation	Symbolic representation of a chemical reaction
Reactants	Substances on the left side of a chemical equation
Products	Substances on the right side of a chemical equation
Stoichiometry	Numerical relationships between reactants and products in a balanced chemical equation
Limiting Reactant	Reactant that has the smallest stoichiometric amount in a reactant mixture. Consequently, this limits the amount of product in a chemical reaction
Excess Reactant	Reactant that is not the limiting reactant
Theoretical Yield	Greatest possible amount of product that can be made in a chemical reaction
Actual Yield	Amount of product actually produced by a chemical reaction
Percent Yield	Percentage of the theoretical yield of a chemical reaction that is actually produced
Synthesis Reaction	Reaction where two reactants combine into one product
Decomposition Reaction	Reaction where one reactant breaks down into multiple products
Single Replacement Reaction	Reaction where one uncombined reactant replaces another in a product compound
Double Replacement Reaction	Reaction where the anions and cations of two reactant compounds switch places and form two entirely new compounds
Combustion Reaction	Reaction where a substance combines with oxygen to form one or more oxygen-containing compounds and emits heat. These reactions are necessary for engines to function.
Solution	Homogenous mixture of two substances
Solvent	Majority component of a solution; the dissolving component
Solute	Minority component of a solution; the dissolved component
Aqueous Solution	Solution where water is the solvent
Concentrated Solution	Solution that contains a large amount of solute relative to the amount of solvent
Dilute Solution	Solution that contains a small amount of solute relative to the solvent
Stock Solution	Highly concentrated form of a solution used in laboratories to make less concentrated solutions
Solubility	Amount of a substance that will dissolve in a given amount of solvent
Miscibility	Ability of two or more substances to fully dissolve in each other at any concentration
Molarity (M)	Amount of solute in moles divided by the volume of the solution in liters
Electrolyte	Substance that dissolves in water to form solutions to conduct electricity
Strong Electrolyte	Substance that completely dissociates into ions when dissolved in water
Weak Electrolyte	Substance that partially dissociates into ions when dissolved in water
Nonelectrolyte	Substance that does not dissociate into ions when dissolved in water
Soluble	Being able to dissolve to a significant extent in water
Insoluble	Being unable to dissolve to a significant extent in water
Precipitation Reaction	Reaction where a solid forms when two solutions are mixed
Precipitate	Solid that forms in a precipitation reaction
Molecular Equation	Equation showing the complete neutral formula for each compound in a reaction
Complete Ionic Equation	Equation that lists individually all of the ions present as reactants or products in a chemical reaction
Net Ionic Equation	Equation that shows only the species that actually change during a chemical reaction
Spectator Ion	Ion that does not participate in a reaction and therefore remains in solution
Enthalpy of Solution	Enthalpy change associated with the formation of a solution
Heat of Hydration	Enthalpy change that occurs when one mole of gaseous solute ions is dissolved in water
Saturated Solution	Solution that contains the exact equilibrium amount of solute
Unsaturated Solution	Solution containing less than the equilibrium amount of solute
Supersaturated Solution	Unstable solution in which more than the equilibrium amount of solute id dissolved
Recrystallization	Technique used to purify solids in which the solid is put into hot solvent until the solution is saturated. When the solution cools, the purified solute comes out of solution
Henry's Law	Solubility of a gas equals the partial pressure of the gas times a constant of proportionality
Molality (m)	Solution concentration expressed as the number of moles of solute per kilogram of solvent
Parts by Mass	Mass of the solute divided by mass of the solution times a multiplication factor
Percent by Mass	Method of expressing parts by mass that used a multiplication factor of one hundred percent
Parts Per Million (ppm)	Method of expressing parts by mass that uses a multiplication factor of 10^6
Parts Per Billion (ppb)	Method of expressing parts by mass that uses a multiplication factor of 10^9
Parts by Volume	Volume of the solute divided by volume of the solution times a multiplication factor
Mole Percent	Mole fraction multiplied by one hundred percent
Colligative Property	Property that depends on the amount of a solute, but not the solute's identity
Raoult's Law	Vapor pressure of a solution equals the mole fraction of the solvent times the vapor pressure of the pure solvent at the same pressure
Vapor Pressure Lowering	Change in vapor pressure that occurs in pure substances upon adding a solute
Ideal Solution	Solution that follows Raoult's Law at all concentrations for both solute and solvent
Freezing Point Depression	When a solute causes a solution to have a lower melting point than the pure solvent
Boiling Point Elevation	When a solute causes a solution to have a higher boiling point than the pure solvent
Osmosis	Flow of solvent from a solution of lower concentration to one of higher solute concentration
Semipermeable Membrane	Membrane that allows some substances to mass through, but not others
Osmotic Pressure	Pressure required to stop osmotic flow
Van't Hoff Factor (i)	Ratio of moles of particles in a solution to moles of formula units dissolved
Colloid (Colloidal Dispersion)	Mixture in which a dispersed substance (similar to a solute) is finely divided but not truly dissolved in a dispersing medium. These mixtures are often opaque and hazy
Aerosol	Colloid where a liquid or solid is dispersed within a gas
Foam	Colloid where a gas is dispersed within a liquid
Emulsion	Colloid where a liquid is dispersed within another liquid
Tyndall Effect	Scattering of light by a colloidal dispersion
Acid	Molecular compound that produces H+ ions in aqueous solution. They have a pH below seven, taste sour, and turn blue litmus red
Binary Acid	Acid composed of hydrogen and a nonmetal; an example includes hydrochloric acid
Oxyacid	Acid composed of hydrogen and an oxyanion
Strong Acid	Acid that completely dissociates in solution
Weak Acid	Acid that partially dissociates in solution
Base	Molecular compound that produces OH- ions in aqueous solution. They have a pH above seven, taste bitter, and turn red litmus blue
Strong Base	Base that completely dissociates in solution
Weak Base	Base that partially dissociates in solution
Amphoteric	When a molecule or ion can act as both an acid and a base
Neutralization Reaction	Reaction where an acid and a base neutralize each other, producing water and a salt
Hydronium Ion	H3O+ ion; formed from the association of water an an H+ ion donated by an acid
Salt	Ionic compound formed in a neutralization reaction by the replacement of an H+ ion from the acid with a cation from the base
Titration	Laboratory procedure in which a substance in a solution of known concentration is reacted with another substance in a solution of unknown concentration in order to determine the unknown concentration
Equivalence Point	Point in titration at which the added solute reacts completely with the solute present in solution
Indicator	Dye whose color depends on the acidity or basicity of the solution
Endpoint	Point of pH change where an indicator changes color
Gas-Evolution Reaction	Reaction in which two aqueous solutions mix and a gas forms, causing bubbling
Redox Reaction	Reaction in which electrons transfer from one reactant to another
Oxidation	Loss of electrons, producing a more positive charge
Reduction	Gain of electrons, producing a more negative charge
Oxidation Number	Positive or negative whole number that represents the "charge" an atom in a compound would have if all shared electrons were assigned to the atom with a greater attraction for those electrons
Oxidizing Agent	Substance that causes the oxidation of another substance in reaction; this is reduced in a redox reaction
Reducing Agent	Substance that causes the reduction of another substance in reaction; this is oxidized in reaction
Activity Series	Listing of metals in order of decreasing ability to oxidize and decreasing tendency to lose electrons
Alkaloids	Organic bases found in plants. They are often poison
Arrhenius Definition	Acids produce H+ ions in aqueous solution; bases produce OH- in aqueous solution
Bronsted-Lowry Definition	Acids donate protons in aqueous solution; bases accept protons in aqueous solution
Conjugate Acid-Base Pair	Two substances related to each other by the transfer of a proton
Conjugate Acid	Any base to which a proton has been added
Conjugate Base	Any acid from which a proton has been removed
Monoprotic Acid	Acid that contains one ionizable proton
Diprotic Acid	Acid that contains two ionizable protons
Triprotic Acid	Acid that contains three ionizable protons
Polyprotic Acid	Acid that contains more than three ionizable protons
Acid Ionization Constant	Equilibrium constant for the ionization reaction of a weak acid. It is used to compare the relative strengths of weak acids, and is symbolized by "K" with a subscript "a."
Autoionization	Process by which water acts as an acid and a base with itself
Ion Product Constant for Water	Equilibrium constant for the autoionization of water. Sometimes called the dissociation constant for water. It is symbolized by "K" with a subscript "w."
Neutral Solution	Solution with equal concentrations of the hydronium and hydroxide ions
Acidic Solution	Solution with a greater concentration of the hydronium ion compared to the hydroxide ion
Basic Solution	Solution with a greater concentration of the hydroxide ion compared to the hydronium ion
pH	Negative logarithm of the concentration of the hydronium ion in a solution. It defines acidity
pOH	Negative logarithm of the concentration of the hydroxide ion in a solution. It defines basicity
Percent Ionization	Ratio of the ionized acid concentration to the initial acid concentration, times one hundred percent
Base Ionization Constant	Equilibrium constant for the ionization reaction of a weak base. It is used to compare the relative strengths of weak acids, and is symbolized by "K" with a subscript "b."
Lewis Acid	Atom, ion, or molecule that is an electron pair acceptor
Lewis Base	Atom, ion, or molecule that is an electron pair donor
Acid Rain	Precipitation with a low pH, created by sulfuric and nitric acid
Buffer	Solution that resists pH change by neutralizing acid or base
Common Ion Effect	Tendency for a common ion to decrease the solubility of an ionic compound or to decrease the ionization of a weak acid or a weak base
Buffer Capacity	Amount of acid or base that can be added to a buffer without causing a large change in pH
Solubility Product Constant	Equilibrium expression for a chemical equation that represents the dissolution of an ionic compound. Symbolized by "K" with the subscript "sp."
Selective Precipitation	Process involving the addition of a reagent to a solution that forms a precipitate with one of the dissolved ions but not the other
Inert	Describes an unreactive element, such as a noble gas, that rarely bonds with other elements
Pressure	Amount of force per unit of area
Barometer	Instrument that measures air pressure
Manometer	Instrument that measures pressure of a gaseous sample
Millimeter of Mercury (mmHG)	Unit of pressure referring to the air pressure required to push a column of mercury to a height of one millimeter in a barometer. One atmosphere equals seven hundred and sixty of these
Torr	Alternative name for the unit of pressure mmHG.
Atmosphere (atm)	Unit of pressure relative to the average pressure at sea level; atmospheric pressure at sea level equals one of these units
Pascal (Pa)	Unit of pressure equal to one newton per square meter. It is the SI unit of pressure
Pounds per Square Inch (psi)	Unit of pressure, where atmospheric pressure equals 14.7 at sea level
Boyle's Law	Volume and pressure are inversely proportional
Charles's Law	Volume and temperature are directly proportional
Gay-Lussac's Law	Pressure and temperature are directly proportional
Avogadro's Law	Volume and amount of substance (in moles) are directly proportional
Ideal Gas Law	Law that combines Boyle's, Charles's, Avogadro's, and Gay Lussac's Law into one comprehensive equation: PV = nRT. P is pressure, V is volume, T is temperature, R is a constant, and n is moles of gas
Ideal Gas	Hypothetical gas that perfectly follows the ideal gas law under all conditions
Ideal Gas Constant	Variable "R" in the ideal gas equation. It equals 0.08206 when pressure is measured in atmospheres
Molar Volume	Volume occupied by one mole of a substance
STP	Standard Temperature and Pressure. Equal to 273 K (or 0° C) and 1.00 atm
Partial Pressure	Pressure due to any individual component of a gas mixture
Dalton's Law of Partial Pressures	Sum of the partial pressures of the components in a gaseous mixture must always equal the total pressure exerted by the gaseous mixture
Hypoxia	Abnormally low levels of blood oxygen. Causes dizziness, headaches, shortness of breath, and eventually death
Oxygen Toxicity	Abnormally high levels of blood oxygen. Causes muscle twitching, tunnel visions, and convulsions
Nitrogen Narcosis	Increased partial pressure of nitrogen in the bloodstream, resulting in symptoms similar to those of intoxication. Also known as "rapture of the deep" or the "Martini effect"
Decompression Sickness	When dissolved gases come out of solution and become bubbles inside the body due to depressurization. Also known as "the bends" or "divers' disease."
Vapor Pressure	Partial pressure of a vapor in dynamic equilibrium with its liquid
Kinetic Molecular Theory	Model of an ideal gas as a collection of point particles in constant motion undergoing completely elastic collisions
Mean Free Path	Average distance that a molecule in a gas travels between collisions
Diffusion	Process by which gas molecules spread out in response to a concentration gradient
Effusion	Process by which molecules escape a container into a vacuum through a small hole
Graham's Law	Ratio of effusion rates between two gases is equal to the square roots of the inverse of the molar masses
Van der Waals Equation	Extrapolation of the ideal gas law that considers the effects of intermolecular forces and particle volume in a nonideal gas
Exothermic Reaction	Reaction that gives off heat into its surroundings (negative change in enthalpy)
Endothermic Reaction	Reaction that absorbs heat from its surroundings (positive change in enthalpy)
Work	Action of a force across a distance
Energy	Capacity to do work
Kinetic Energy	Energy associated with an object's motion
Potential Energy	Energy associated with an object's position or composition
Thermal Energy	Energy associated with an object's temperature
Chemical Energy	Energy associated with an object's electrons and bonds
Law of Conservation of Energy	Energy is neither created nor destroyed during a chemical reaction
System	Portion of the universe that is singled out for investigation
Surroundings	Everything in the universe that exits outside the system under investigation
Joule (J)	SI unit of energy. Equal to kg × m^2/s^2
Calorie (cal)	Unit of energy defined as the amount of energy required to raise the temperature of one gram of water by one Celsius degree. Equal to 4.184 Joules
Calorie (Cal)	Unit of energy equal to one thousand lowercase "c" calories. Also called the kilocalorie (kcal)
Kilowatt-Hour (kWh)	Unit of energy used to express large amounts of energy produced by the flow of electricity. Often used by power companies to determine electrical usage. Equal to 3.60 × 19^6 J
Thermodynamics	General study of energy and its conversion
Internal Energy (E)	Sum of the kinetic and potential energies of all of the particles that compose a system
State Function	Function whose value depends only on the state of the system, not how the system got to that state
Heat	Energy in transfer to or from a thermodynamic system
Thermal Equilibrium	State of no additional net transfer of heat
Heat Capacity (C)	Quantity of heat required to change a system's temperature by one Celsius degree
Specific Heat Capacity	Amount of heat required to heat one gram of a substance by one Celsius degree
Molar Heat Capacity	Amount of heat required to heat one mole of a substance by one Celsius degree
Pressure-Volume Work	Work that occurs when a volume change takes place against an external pressure
Calorimetry	Experimental procedure used to measure the heat that evolves in a chemical reaction
Bomb Calorimeter	Device designed to measure the change in internal energy for combustion reactions
Enthalpy (H)	Sum of the internal energy of a system and the product of its pressure and volume
Enthalpy of Reaction (Heat of Reaction)	Enthalpy change for a chemical reaction
Coffee-Cup Calorimeter	Device used to measure enthalpy of reaction for aqueous solutions
Hess's Law	If a chemical equation can be expressed as the sum of a series of steps, then the heat of reaction for the overall equation is the sum of the heats of reactions for each step
Standard Enthalpy Change	Change in enthalpy for a process where all reactants and products are at standard state
Standard Enthalpy (Heat) of Formation	Change in enthalpy when one mole of a compound forms from its constituent elements in their standard states
Standard State	Reference point of a material or substance used to calculate its properties under different conditions
Quantum-Mechanical Model	Model that explains behavior of microscopic particles like electrons and protons
Electromagnetic Radiation	Energy embodied in oscillating electric and magnetic fields
Amplitude	Vertical height of a wave's crest (or depth of its trough)
Wavelength (λ)	Distance between adjacent crests or analogous points on a wave. Represented by a lambda
Frequency (v)	Number of cycles that pass through a stationary point in a given time period. Measured in Hertz
Electromagnetic Spectrum	Range of the wavelengths of all possible electromagnetic radiation
Gamma Radiation (γ)	Form or electromagnetic radiation with the shortest wavelength
X-Rays	Form of electromagnetic radiation with wavelengths longer than those of gamma rays; used in medical imaging
Ultraviolet Radiation (UV)	Form of electromagnetic radiation with wavelengths shorter than visible light
Visible Light	Form of electromagnetic radiation that can be detected by the human eye
Infrared Radiation (IR)	Form of electromagnetic radiation with longer wavelengths than visible light
Microwaves	Form of electromagnetic radiation with wavelengths slightly longer than infrared radiation
Radio Waves	Form of electromagnetic radiation with the longest wavelengths
Interference	Superposition of two or more waves in overlapping space, resulting in their interaction
Constructive Interference	Interference resulting in an increase in amplitude
Destructive Interference	Interference resulting in a decrease in amplitude
Diffraction	When a wave, emerging from an aperture or coming around a corner, spreads out to form a new front
Photoelectric Effect	Observation that many metals emit electrons when light falls upon them
Photon (Quantum)	Smallest possible packet of electromagnetic radiation
Emission Spectrum	Range of wavelengths emitted by a particular substance
Absorption Spectrum	Range of wavelengths absorbed by a particular substance
De Broglie Relation	Observation that the wavelength of a particle is inversely proportional to its momentum
Heisenberg's Uncertainty Principle	Principle stating that due to the wave-particle duality, it is fundamentally impossible to precisely determine both the position and momentum of a particle at a given time
Deterministic	Characteristic of classical motion; implies that present circumstances determine future events
Indeterminacy	Principle asserting that present circumstances do not necessarily determine future events in the quantum-mechanical realm
Orbital	Probability distribution map, based on the quantum-mechanical model of the atom, used to describe the likely position of an electron in an atom; also, an allowed energy state for an electron
Wave Function	Mathematical function that describes the wavelike nature of the electron
Quantum Numbers	One of four interrelated numbers that determine the shape and energy of orbitals
Principal Quantum Number (n)	Integer that specifies the overall size and energy of an orbital. The higher this number, the greater the average distance between the electron and the nucleus and the higher its energy
Angular Momentum Quantum Number (l)	Integer that determines the overall shape of an orbital
Magnetic Quantum Number (ml)	Integer that specifies the orientation of an orbital
Spin Quantum Number (s)	Integer that denotes the electrons spin (1/2 or -1/2)
Principal Level (Principal Shell)	Group of orbitals with the same principal quantum number
Sublevel (Subshell)	Orbitals in the same principal level with the same principal and angular momentum quantum numbers
Probability Density	Probability of finding an electron at a point in space, expressed by a three-dimensional plot of the wave function squared
Radial Distribution Function	Mathematical function - corresponding to a specific orbital - that represents the total probability of finding an electron within a thin spherical shell at a distance of "r"
Node	Point where the probability density and radial distribution function both pass through zero; for a wave, points where the amplitude is zero
Phase	Sign of the amplitude of the wave; positive or negative
Periodic Property	Property of an element that is predictable based on its position in the periodic t able
Electron Configuration	Notation that shows the particular orbitals that are occupied by electrons in an atom
Ground State	Lowest energy state in an atom, ion, or molecule
Pauli Exclusion Principle	No two electrons in an atom can have the same four quantum numbers
Degenerate Orbitals	Orbitals with the same principal quantum number that have the same energy
Coulomb's Law	The potential energy between two charged particles is proportional to the product of the charges divided by the square of the distance that separates the charges
Shielding	Repulsive effect on an electron by other electrons in lower-energy orbitals that screen it from the full effects of the attractive forces of the nucleus
Effective Nuclear Charge	Actual nuclear charge experienced by an electron, defined as the charge of the nucleus plus the charge of the shielding electrons
Penetration	Phenomenon of some higher-level atomic orbitals having significant amounts of probability within the space occupied by orbitals of lower energy levels
Aufbau Principle	Principle that indicates the pattern of orbital filling in an atom
Hund's Rule	When electrons fill degenerate orbitals, they first fill them singly with parallel spins
Valence Electrons	Electrons in the outermost principal energy level
Core Electrons	Electrons that are not in the valence shell
Atomic Radius	Average bonding radius of an atom; this increases as you move down a column and decreases as you move to the right in a row
Covalent Radius
Van der Waals Radius
Paramagnetic
Diamagnetic
Ionization Energy
Electron Affinity
Metallic Character
Chemical Bond
Ionic Bond
Ionic Compound
Covalent Bond
Molecular Compound
Metallic Bond
Lewis Model
Octet
Duet
Octet Rule
Lattice Energy
Born-Haber Cycle
Bonding Pair
Lone Pair (Nonbonding Electrons)
Single Bond
Double Bond
Triple Bond
Polar Covalent Bond
Nonpolar Covalent Bond
Electronegativity
Dipole Moment
Percent Ionic Character
Resonance Structure
Resonance Hybrid
Formal Charge
Free Radical
Incomplete Octet
Expanded Octet
Bond Energy
Bond Length
VSEPR (Valence Shell Electron Pair Repulsion) Theory
Electron Groups
Molecular Geometry
Linear Geometry
Trigonal Planar Geometry
Tetrahedral Geometry
Trigonal Bipyramidal Geometry
Octahedral Geometry
Electron Geometry
Trigonal Pyramidal Geometry
Bent Geometry
Seesaw Geometry
T-Shaped Geometry
Square Pyramidal Geometry
Square Planar Geometry
Valence Bond Theory
Hybridization
Hybrid Orbitals
Pi (π) Bond
Sigma (σ) Bond
Molecular Orbital Theory
Bonding Orbital
Antibonding Orbital
Bond Order
Nonbonding Orbital
Crystalline
Amorphous
Intermolecular Force
Dispersion Force (London Force)
Dipole-Dipole Force
permanent Dipole
Hydrogen Bond
Ion-Dipole Force
Surface Tension
Viscosity
Capillary Action
Vaporization
Condensation
Volatile
Nonvolatile
Heat of Vaporization
Vapor Pressure
Boiling Point
Normal Boiling Point
Critical Temperature
Critical Pressure
Sublimation
Deposition
Melting (Fusion)
Freezing
Melting Point
Heat of Fusion
Heat of Sublimation
Phase Diagram
Triple Point
Critical Point
Graphene
X-Ray Diffraction
X-Ray Crystallography
Crystalline Lattice
Unit Cell
Simple Cubic
Body-Centered Cubic
Face-Centered Cubic
Coordination Number
Packing Efficiency
Hexagonal Closest Packing
Molecular Solids
Ionic Solids
Atomic Solids
Nonbonding Atomic Solids
Metallic Atomic Solids
Network Covalent Solids
Polymorphs
Graphite
Diamond
Fullerenes
Nanotubes
Silicates
Quartz
Ceramics
Clay
Portland Cement
Concrete
Glass
Vitreous Silica (Fused Silica)
Soda-Lime Glass
Borosilicate Glass (Pyrex)
Leaded Glass
Band Theory
Valence Band
Conduction Band
Band Gap
Semiconductor
N-Type Semiconductor
P-Type Semiconductor
P-N Junction
Diode
Polymer
Monomer
Addition Polymer
Condensation Polymer
Dimer
Rate Law
Rate Constant
Reaction Order (n)
Overall Order
Integrated Rate Law
Half Life (Reaction)
Arrhenius Equation
Activation Energy
Frequency Factor
Activated Complex (Transition State)
Exponential Factor
Collision Model
Orientation Factor
Collision Frequency
Reaction Mechanism
Elementary Step
Reaction Intermediate
Molecularity
Unimolecular
Bimolecular
Termolecular
Rate-Determining Step
Catalyst
Homogenous Catalysis
Heterogenous Catalysis
Enzyme
Active Site
Substrate
Reversible
Dynamic Equilibrium
Equilibrium Constant
Law of Mass Action
Reaction Quotient
Le Chatelier's Principle

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