n = m / MpHPV = nRTQ → K

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01 Foundations: Chapters 1–6Use scientific reasoning, mathematics, measurement, and atomic models. 6chapters

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Chemistry Learning Hub: Lessons, Tests and 1,084 Flashcards: a single starting point that brings together the lessons, worksheets, practice tests, and review material for this subject, arranged in a sensible order so you can work through it from start to finish.

Chemistry terms and definitions

403 chemistry terms defined in plain language, grouped by topic. This is the reference half of the flashcard deck above, written out so you can search the page for a term, revise without clicking through cards, or print the set.

Ch. 01 · Chemistry and Scientific Problem-Solving

Control condition

A control condition, also called a comparison condition, provides the baseline needed to interpret a result.

Controlled variables

Controlled variables are other factors kept as constant as practical.

Inference

An inference is an interpretation of what that observation may mean.

Law

Laws, Theories, and Models A scientific law summarizes a repeatedly observed relationship, often in words or an equation.

Macroscopic view

Three Ways to Represent One Event Chemists move among three complementary views: The macroscopic view describes what can be directly observed or measured.

Observation

Evidence, Explanations, and Experiments An observation reports what is detected with the senses or an instrument.

Particle view

The particle view explains the atoms, ions, or molecules responsible for the observation.

Qualitative

Observations may be qualitative, such as a color change, or quantitative, such as a temperature increase of 3.8 ^ C.

Quantitative

Observations may be qualitative, such as a color change, or quantitative, such as a temperature increase of 3.8 ^ C.

Symbolic view

The symbolic view represents the event with chemical symbols, formulas, equations, graphs, or numbers.

Ch. 02 · Essential Mathematics for Chemistry

Exact number

An exact number comes from counting objects or from a definition, so it carries no measurement uncertainty and does not limit precision.

Extrapolation

Extrapolation extends beyond the measured range and carries more uncertainty because the pattern may change.

Interpolation

Interpolation estimates a value between measured points.

Proportion

A proportion applies when two ratios are equal.

Rate

A ratio compares two quantities, and a rate is a ratio whose quantities have different units.

Ratio

A ratio compares two quantities, and a rate is a ratio whose quantities have different units.

Significant figures

Measured Precision and Significant Figures Measured digits communicate precision.

Ch. 03 · Scientific Measurements and Laboratory Tools

Accurate

A result is accurate when it agrees closely with a reliable reference value under comparable conditions.

Analog instrument

For a clearly marked analog instrument, record the certain digits and one reasonable estimated digit beyond the smallest graduation.

Centi-

Going the other way, centi- means one hundredth, so a centimeter is (1)/(100) of a meter, and milli- means one thousandth, so a milligram is (1)/(1000) of a gram.

Conversion factor

A conversion factor is a ratio of equivalent quantities, such as 1000 mL/1 L.

Degrees Celsius

Temperature in many laboratory contexts is read in degrees Celsius.

Digital instrument

For a digital instrument, record the displayed digits after the reading stabilizes.

Estimate

You record 24.5 mL: read to the smallest marked division, then estimate one more digit between the marks.

Graduated cylinder

A graduated cylinder is a tall, narrow tube with volume markings up the side.

Intensive property

For a uniform material under stated conditions, density is an intensive property: changing sample size changes mass and volume together, not their ratio.

International System of Units

The International System of Units, or SI (from the French Système International), is the modern international standard used in science.

Kilo-

Kilo- means one thousand times the base, so a kilometer is 1000 meters and a kilogram is 1000 grams.

Laboratory balance

A laboratory balance determines mass.

Mass

Mass measures inertia—how strongly an object resists a change in motion.

Measurement uncertainty

Limited resolution is one source of measurement uncertainty, the doubt associated with a reported result.

Meniscus

That curved surface is the meniscus.

Metric system

The metric system is a family of decimal-based measurement systems.

Milli-

Going the other way, centi- means one hundredth, so a centimeter is (1)/(100) of a meter, and milli- means one thousandth, so a milligram is (1)/(1000) of a gram.

Parallax

Looking from above or below causes parallax.

Precise

Measurements are precise when they cluster closely together.

Prefixes

The metric system stretches each base unit up and down with prefixes, short word-parts that multiply or divide the unit by powers of ten.

Random error

Trial-to-trial scatter is a form of random error.

Resolution

The resolution is the smallest change an instrument can display or distinguish.

Systematic error

A consistent directional bias, such as a miscalibrated balance or always viewing a meniscus from above, is systematic error.

Volume

Volume is the space occupied by a sample.

Water displacement

This is water displacement: V_object=V_final-V_initial.

Ch. 04 · States, Properties, and Changes of Matter

Boiling

Vaporization at the surface is evaporation, while vaporization throughout a liquid at its boiling point is boiling.

Changes of state

These changes of state have specific names and energy directions.

Chemical property

A chemical property describes how readily, or under what conditions, a substance can form new substances.

Closed system

In a closed system, energy may cross but matter does not.

Condensation

Condensation turns a gas into a liquid as the substance releases energy.

Conservation of mass

The conservation of mass states that the total mass remains constant through an ordinary physical or chemical change when all matter in the defined system is included.

Deposition

The reverse of sublimation, a gas turning straight into a solid, is called deposition.

Evaporation

Vaporization at the surface is evaporation, while vaporization throughout a liquid at its boiling point is boiling.

Extensive properties

Mass and volume are extensive properties, so they change when the sample amount changes.

Flammability

Flammability, the ability to burn, is a chemical property.

Freezing

Freezing turns a liquid into a solid as the substance transfers energy to its surroundings.

Gas

In a gas, the particles are far apart and move freely through all the space they are given, so a gas has no shape of its own and no fixed volume.

Intensive properties

Density and melting point are intensive properties: they do not depend on the amount of a uniform sample.

Liquid

In a liquid, the particles stay close but are free to slide past one another, the way marbles shift around in a bag.

Melting

Melting turns a solid into a liquid as the substance absorbs energy from its surroundings.

Open system

In an open system, matter and energy may cross that boundary.

Physical property

A physical property is something you can observe or measure without changing its chemical identity.

Reaction evidence

Reaction evidence is a set of observations that supports this conclusion after plausible physical explanations have been considered.

Reactivity

So is reactivity, which describes response to another substance or condition, such as a metal reacting with acid or iron combining with oxygen.

Solid

In a solid, the particles stay close together and vibrate around relatively fixed positions.

States of matter

Matter usually appears in one of three familiar forms called the states of matter, and the difference between them comes down to two things: how closely the particles are spaced and how freely they move.

Sublimation

A substance can even skip the liquid stage: sublimation takes a solid straight to a gas.

Surroundings

The system is the matter chosen for study, and the surroundings are everything outside its system boundary.

System

The system is the matter chosen for study, and the surroundings are everything outside its system boundary.

System boundary

The system is the matter chosen for study, and the surroundings are everything outside its system boundary.

Vaporization

Vaporization turns a liquid into a gas as the substance absorbs energy.

Ch. 05 · Atoms, Elements, and the Periodic Table

Contamination

Contamination means radioactive material is present where it should not be, such as on skin, clothing, or a surface.

Electrolytes

The ions in that box have a clinical name: electrolytes.

Electrons

Electrons occupy probability regions around the nucleus.

Family

Each vertical column is a periodic group (also called a family).

Isotopes

These different versions are called isotopes.

Main-group elements

For the main-group elements emphasized in this chapter, members of a column have similar outer-electron patterns and, with a few exceptions, the same number of valence electrons.

Metalloids

Along the stair-step boundary are elements often called metalloids.

Metals

Most are metals, which generally conduct heat and electricity well and are malleable as solids.

Neutrons

It contains a tiny, dense nucleus made of protons and neutrons.

Nonmetals

Nonmetals occupy the upper right plus hydrogen.

Nucleus

It contains a tiny, dense nucleus made of protons and neutrons.

Periodic group

Each vertical column is a periodic group (also called a family).

Periodic table

All the known elements are organized on one chart: the periodic table.

Periods

The horizontal rows are called periods.

Protons

It contains a tiny, dense nucleus made of protons and neutrons.

Symbol

The modern periodic table contains 118 officially named elements, and each has a one- or two-letter symbol.

Valence electrons

For the main-group elements emphasized in this chapter, members of a column have similar outer-electron patterns and, with a few exceptions, the same number of valence electrons.

Ch. 06 · Electron Arrangement and Periodic Trends

Atomic radius

Atomic radius is a measure of atomic size.

Core electrons

Core electrons occupy filled inner energy levels.

First ionization energy

First ionization energy is the energy required to remove the outermost electron from a gaseous neutral atom:

Full electron configuration

A full electron configuration lists every occupied sublevel.

Isoelectronic

Comparisons are most direct when the species are related or isoelectronic, meaning they contain the same number of electrons.

Noble-gas configuration

A noble-gas configuration replaces the filled inner configuration with the symbol of the previous noble gas in brackets.

Principal energy level

Levels, Sublevels, and Orbitals A principal energy level is labeled by n=1,2,3,.

Probability distribution

Quantum mechanics describes an electron by a probability distribution: a region in which the electron is likely to be found.

Sublevel

Levels, Sublevels, and Orbitals A principal energy level is labeled by n=1,2,3,.

Ch. 07 · Chemical Bonding: From Electrons to Compounds

Chemical formula

A chemical formula identifies elements and their relative numbers.

Covalent bonds

Shared electron pairs form covalent bonds.

Electronegative

The more electronegative atom draws electron density toward itself, creating a polar covalent bond.

Formula unit

NaCl therefore describes a formula unit, the lowest whole-number ion ratio in the lattice, rather than one sodium chloride molecule.

Hydration shells

These hydration shells stabilize the separated ions.

Lewis symbol

A Lewis symbol places dots around an element symbol to show its valence electrons.

Metallic bond

A metallic bond is the collective electrostatic attraction between metal cations and mobile, delocalized valence electrons.

Nonelectrolyte

Sugar can dissolve while remaining as neutral molecules, so it is a nonelectrolyte.

Octet rule

Chemists call this recurring pattern the octet rule.

Polar covalent bond

The more electronegative atom draws electron density toward itself, creating a polar covalent bond.

Sodium chloride

Take table salt, sodium chloride (NaCl).

Ch. 08 · Molecular Shape, Polarity, and Intermolecular Forces

Bond dipole

From Bond Dipoles to Molecular Polarity A bond dipole results when bonded atoms attract shared electrons unequally.

Dipole–dipole attractions

Dipole–Dipole Attractions Polar molecules experience dipole–dipole attractions: the partially positive region of one molecule attracts the partially negative region of another.

Electron domain

Each region is an electron domain.

Electron-domain geometry

Electron-Domain Geometry and Molecular Shape The electron-domain geometry describes the arrangement of all domains, including lone pairs.

Hydrogen bonding

Hydrogen Bonding Hydrogen bonding is a strong, directional type of dipole–dipole attraction.

Intermolecular forces

Intermolecular Forces: Attractions Between Particles Covalent and ionic bonds build particles or lattices.

Ion–dipole attraction

Ion–Dipole Attractions An ion can attract the oppositely charged end of a polar molecule through an ion–dipole attraction.

Linear geometry

Two domains point in opposite directions, giving linear geometry near 180°.

London dispersion forces

London Dispersion Forces All atoms and molecules experience London dispersion forces.

Molecular shape

Electron-Domain Geometry and Molecular Shape The electron-domain geometry describes the arrangement of all domains, including lone pairs.

Nonpolar

It is nonpolar when no meaningful bond dipoles exist or when the bond dipoles cancel.

Polar

A molecule’s polarity requires a second question: how do all bond dipoles add in three dimensions?

Polarizability

Dispersion generally strengthens as electron clouds grow larger and gain polarizability.

VSEPR model

From a Lewis Structure to Three-Dimensional Shape The VSEPR model—valence-shell electron-pair repulsion—predicts molecular shape by placing regions of electron density around a central atom as far apart as practical.

Ch. 09 · The Mole and Molar Mass

Avogadro constant

This number is the Avogadro constant, written N_A.

Ch. 10 · Chemical Composition and Formulas

Anhydrous salt

When a hydrate is heated carefully, water is removed and the anhydrous salt remains:

Heating to constant mass

This is called heating to constant mass.

Mass percent

The mass percent of an element is the percentage of a compound’s total mass contributed by that element:

Ch. 11 · Chemical Reactions and Equations

Balanced

A chemical equation is balanced when each element has the same number of atoms on the left as on the right.

Balanced equation

After coefficients are chosen so every atom count agrees, the result is a balanced equation.

Chemical reaction

A chemical reaction turns one set of substances into a different set.

Combustion

Combustion is a substance reacting with oxygen and releasing energy.

Complete ionic equation

Splitting strong, soluble electrolytes into ions gives the complete ionic equation: Ag^+(aq)+NO_3^-(aq)+Na^+(aq)+Cl^-(aq) → AgCl(s)+Na^+(aq)+NO_3^-(aq).

Conservation of atoms

This conservation of atoms is why a valid chemical equation must account for every atom on both sides.

Decomposition

Decomposition is the reverse pattern, one reactant breaking into two or more products.

Double-replacement

In a double-replacement reaction two compounds swap partners, and the swap often produces a precipitate.

Law of conservation of mass

The law of conservation of mass says that atoms are only rearranged in a chemical reaction, never created and never destroyed.

Products

The starting substances are the reactants, and the new substances that form are the products.

Reactants

The starting substances are the reactants, and the new substances that form are the products.

Reversible reaction

A double arrow, ⇌, indicates a reversible reaction: both forward and reverse processes occur.

Single-replacement

In a single-replacement reaction one element kicks another out of a compound and takes its spot.

Skeleton equation

A skeleton equation shows the correct reactant and product formulas before coefficients have been adjusted.

Spectator ions

They are spectator ions.

State symbol

Each state symbol—(s), (l), (g), or (aq)—records the physical state or whether a substance is dissolved in water.

Synthesis

Synthesis takes two or more reactants and forms a single product in the simplified pattern, so the arrow points from many to one.

Yields

The arrow is read as yields, so reactants → products simply means "these turn into those."

Ch. 12 · Reaction Types, Aqueous Reactions, and Redox

Activity series

An activity series ranks elements by their tendency to react or lose electrons.

Combustion reaction

A combustion reaction involves rapid reaction with oxygen and usually releases energy as heat and often light.

Complete combustion

In complete combustion, a hydrocarbon or an oxygen-containing organic compound forms carbon dioxide and water when enough oxygen is available: fuel+O_2 → CO_2+H_2O.

Decomposition reaction

In a decomposition reaction, one reactant forms two or more products: AB → A+B.

Double-replacement reaction

A double-replacement reaction is often represented as AB+CD → AD+CB.

Incomplete combustion

When oxygen is limited, incomplete combustion may produce carbon monoxide, elemental carbon (soot), or a mixture of carbon-containing products.

No net ionic reaction

If both proposed products remain strong soluble electrolytes, all ions stay separate in solution and there is generally no net ionic reaction.

Oxidation numbers

Oxidation numbers are bookkeeping values that help track electron ownership.

Reaction type

A reaction type describes the broad way in which reactants are rearranged.

Redox reaction

A redox reaction contains both oxidation and reduction.

Reducing agent

The reducing agent causes another species to be reduced by giving up electrons.

Single-replacement reaction

A single-replacement reaction has the general pattern A+BC → AC+B.

Solubility table

A solubility table summarizes observed patterns and lets you predict whether a proposed ionic product remains aqueous or forms a solid.

Synthesis reaction

In a synthesis reaction, two or more reactants combine to form one main product: A+B → AB.

Ch. 13 · Stoichiometry, Limiting Reactants, and Yield

Mass-to-mass path

This sequence is the mass-to-mass path.

Ch. 14 · Energy, Enthalpy, and Calorimetry

Calorimeter heat capacity

The calorimeter heat capacity, C_cal, has units such as J/°C: q_cal=C_calΔ T.

Calorimetry

Calorimetry is the measurement of heat transfer.

Energy

Energy is the capacity to do work or transfer heat.

Heat

Heat, represented by q, is energy transferred because of a temperature difference.

Hess’s law

Hess’s law states that when chemical equations are added, their enthalpy changes are added.

Temperature

Temperature is related to the average kinetic energy of the particles in a sample.

Ch. 15 · Reaction Rates and Chemical Kinetics

Collision theory

Collision theory explains reaction rate in terms of particle encounters.

Concentration effect

This concentration effect is a collision-frequency explanation, not a promise that every reaction will respond by the same factor.

Effective collision

An effective collision must satisfy two conditions: the collision energy must be at least the activation energy, and the particles must approach with a suitable orientation.

Elementary steps

A reaction mechanism is the proposed sequence of elementary steps.

Enzyme

An enzyme is a biological catalyst, usually a protein.

Intermediate

When elementary steps are added: species produced in one step and consumed in another cancel, the remaining equation must equal the overall reaction, a species produced and later consumed is an intermediate, and a species consumed and later regenerated is a catalyst.

Method of initial rates

The method of initial rates compares experiments performed at the same temperature.

Rate law

A rate law is an experimentally determined relationship between rate and reactant concentrations: rate=k[A]^m[B]^n where: k is the rate constant, m is the order with respect to A, n is the order with respect to B, and m+n is the overall reaction order.

Rate-determining step

A step that limits the observed rate is often called the rate-determining step.

Reaction mechanism

A reaction mechanism is the proposed sequence of elementary steps.

Reaction rate

A reaction rate describes how quickly reactants disappear or products appear.

Temperature effect

This temperature effect changes the rate constant for a given reaction.

Ch. 16 · Chemical Equilibrium

Catalyst at equilibrium

A catalyst at equilibrium lowers activation energy for both forward and reverse pathways.

Dynamic equilibrium

The system has reached dynamic equilibrium.

Heterogeneous equilibrium

An equilibrium involving more than one phase is a heterogeneous equilibrium.

Homogeneous equilibrium

When every reacting species occupies the same phase, the system is a homogeneous equilibrium.

Le Châtelier’s principle

Le Châtelier’s principle states that when a system at equilibrium is disturbed, it shifts in the direction that partially opposes the disturbance.

Reaction quotient

The reaction quotient, Q, has the same algebraic form as K but uses current concentrations or partial pressures, whether or not the system is at equilibrium.

Ch. 17 · Gases, Liquids, Solids, and Phase Behavior

Adhesion

Adhesion is attraction between unlike substances.

Amorphous solid

An amorphous solid lacks long-range repeating order.

Cohesion

Cohesion is attraction between like particles.

Crystalline solid

A crystalline solid has long-range repeating order.

Normal boiling point

The normal boiling point is the boiling temperature at: 1 atm.

Surface tension

Surface tension is the tendency of a liquid surface to resist increasing its area.

Unit cell

The repeating structural unit of a crystal is a unit cell.

Vapor pressure

The pressure exerted by vapor at liquid–vapor equilibrium is the vapor pressure.

Viscosity

Viscosity is resistance to flow.

Ch. 18 · Solutions, Solubility, and Concentration

Concentrated

Dilute and concentrated are qualitative comparison words: dilute: relatively little solute per amount of solution, concentrated: relatively much solute per amount of solution.

Dilute

Dilute and concentrated are qualitative comparison words: dilute: relatively little solute per amount of solution, concentrated: relatively much solute per amount of solution.

Dilution

A dilution adds solvent while keeping the amount of solute constant: n_solute before=n_solute after.

Hydration

When water is the solvent, it is called hydration.

Immiscible

Two liquids that separate into layers are immiscible.

Miscible

Two liquids that mix in all proportions are miscible.

Molality

Molality, symbol m, is moles of solute per kilogram of solvent: m= n_solute kg solvent.

Rate of dissolving

The rate of dissolving describes how quickly solute enters solution.

Solubility

Solubility describes the maximum amount that can be dissolved under specified conditions.

Solvation

The surrounding process is called solvation.

Tyndall effect

The scattering of a visible light beam by colloidal particles is called the Tyndall effect.

Ch. 19 · Reactions in Aqueous Solution

Driving forces

In this chapter, look for three common driving forces: an insoluble solid, called a precipitate, forms a weakly ionized product, especially liquid water, forms a gas forms and escapes from the solution.

Solubility rules

Solubility rules are compact experimental patterns used to predict whether an ionic compound is likely to remain aqueous or form a solid.

Ch. 20 · Acids, Bases, and the pH Scale

Amphiprotic

Water can donate or accept a proton, so it is amphiprotic.

Arrhenius acid

An Arrhenius acid increases hydronium concentration in water, and an Arrhenius base increases hydroxide concentration in water.

Arrhenius base

An Arrhenius acid increases hydronium concentration in water, and an Arrhenius base increases hydroxide concentration in water.

Conjugate acid–base pairs

The products form conjugate acid–base pairs: two species in a pair differ by one proton.

Hydronium

In an acidic solution, the important excess particle is hydronium, H_3O^+.

Hydroxide

In a basic solution, the important excess particle is often hydroxide, OH^-.

Indicator

Because you cannot see H^+, chemists use an indicator, a substance that changes color depending on the acidity around it.

Litmus paper

The classic one is litmus paper.

PH scale

The pH scale compresses an enormous range of hydronium amounts into manageable numbers.

Salt

The ionic compound associated with the remaining ions is called a salt.

Weak acid

A weak acid ionizes only partly.

Ch. 21 · Buffers and Titrations

Analyte

The solution being analyzed is the analyte.

Buffer capacity

Buffer capacity is the amount of acid or base a buffer can absorb before its pH changes sharply.

Buffer range

Buffer range is the pH interval over which the conjugate pair works effectively.

Conjugate acid–base pair

The pair HA/A^- is called a conjugate acid–base pair.

Half-equivalence point

The Half-Equivalence Insight During the titration of a weak acid with a strong base, the half-equivalence point occurs when half of the original weak acid has been converted to its conjugate base.

Henderson–Hasselbalch equation

The Henderson–Hasselbalch equation connects buffer pH with the conjugate-pair ratio: pH=pK_a+ (([A^-])/([HA])).

Titrant

The solution delivered from the burette is the titrant.

Titration

A titration determines an unknown amount or concentration by reacting it with a measured amount of a solution whose concentration is known.

Titration curve

A titration curve plots pH against the volume of titrant added.

Ch. 22 · Batteries, Electrolysis, and Corrosion

Cell notation

Electrochemical cells can be represented compactly with cell notation.

Cell potential

The electrical driving force of a cell is its cell potential, measured in volts.

Corrosion

Corrosion is the unwanted oxidation of a material by its environment.

Electrolytic cell

An electrolytic cell uses an external power source to force a nonspontaneous redox reaction.

Galvanic cell

A voltaic cell, also called a galvanic cell, uses a spontaneous redox reaction to produce electrical energy.

Half-reactions

The reaction can be separated into two half-reactions: Zn(s) → Zn^2+(aq)+2e^- and Cu^2+(aq)+2e^- → Cu(s).

Oxidation number

An oxidation number is a bookkeeping value that helps identify electron transfer.

Salt bridge

The salt bridge contains mobile ions that migrate to maintain approximate electrical neutrality:

Voltaic cell

A voltaic cell, also called a galvanic cell, uses a spontaneous redox reaction to produce electrical energy.

Ch. 23 · Carbon and Organic Chemistry

Addition polymerization

In addition polymerization, alkene monomers link as their double bonds open.

Alkanes

Alkanes contain only carbon–carbon single bonds.

Alkenes

Alkenes contain at least one carbon–carbon double bond.

Alkynes

Alkynes contain at least one carbon–carbon triple bond.

Carbonyl group

Both aldehydes and ketones contain a carbonyl group, C=O.

Catenation

This ability of an element to bond repeatedly to itself is called catenation.

Condensation polymerization

In condensation polymerization, monomers with two reactive functional groups join while small molecules are eliminated.

Condensation reaction

A condensation reaction joins molecules while eliminating a small molecule, often water.

Functional group

A functional group is a recurring arrangement of atoms that gives a molecule characteristic properties and reactions.

Hydrocarbon

A hydrocarbon contains only carbon and hydrogen.

Hydrolysis

The reverse process, in which water helps split a bond, is called hydrolysis.

Monomers

The smaller starting molecules are monomers.

Polymer

A polymer is a large molecule made from many repeating units.

Saturated hydrocarbons

They are called saturated hydrocarbons because they contain the maximum number of hydrogen atoms possible for that open-chain carbon framework.

Structural isomers

Structural isomers, also called constitutional isomers, have the same molecular formula but different atom-to-atom connectivity.

Unsaturated

Alkenes and alkynes are unsaturated because their multiple bonds can undergo reactions that add atoms across the bond.

Ch. 24 · Chemistry of Life

Active site

The substrate interacts with the enzyme’s active site.

Amino acids

Proteins are polymers of amino acids.

Amphipathic

Such a molecule is amphipathic: it contains both water-compatible and water-excluding regions.

Denaturation

Denaturation is the loss of a protein’s functional three-dimensional structure.

Disaccharide

Two monosaccharides can join to form a disaccharide.

Hydrolysis reaction

A hydrolysis reaction uses water to split a bond.

Lipids

Lipids are a diverse group of molecules with large nonpolar regions.

Metabolism

Metabolism includes all chemical reactions in a living system.

Monosaccharide

A monosaccharide is a simple sugar, such as glucose.

Nucleic acids

DNA and RNA are nucleic acids.

Nucleotides

Their monomers are nucleotides.

Osmosis

Osmosis is the net movement of water across a selectively permeable membrane toward the side with the greater effective concentration of dissolved particles that cannot readily cross.

Peptide bonds

Amino acids join through peptide bonds to form polypeptides.

Polymers

Large molecules made from repeating or related units are polymers.

Polysaccharides

Long chains of sugar units form polysaccharides.

Ribozymes

Some RNA molecules also act as catalysts and are called ribozymes.

Saturated

Fatty acids may be saturated, containing no carbon–carbon double bonds, or unsaturated, containing one or more carbon–carbon double bonds.

Substrate

A reactant that binds to an enzyme is called a substrate.

Ch. 25 · Chemistry in the Home, Food, and Health

Active ingredients

A medicine product may contain one or more active ingredients, which produce the intended therapeutic effects, plus inactive ingredients that help with formulation, stability, taste, color, or delivery.

Amphiphilic

Soap and detergent molecules are amphiphilic: they contain a polar or charged hydrophilic region and a nonpolar hydrophobic region.

Antacid

An antacid is one familiar example.

Dose

The dose is the amount actually administered.

Emulsion

The resulting mixture can be an emulsion, with droplets of one liquid dispersed through another.

Fermentation

Fermentation uses microbial reactions to transform food components, as in yogurt, bread, and many preserved foods.

Label compatibility rule

The label compatibility rule turns that warning into a repeatable decision.

Micelles

In water, they can surround small oil droplets in structures called micelles.

Oxidative rancidity

Oxidative rancidity changes fats through reactions with oxygen and can produce unwanted odors or flavors.

Strength

The strength tells how much active ingredient is present per tablet, capsule, measured volume, or other dosage unit.

Ch. 26 · Environmental Chemistry and Green Design

Dose–response relationship

A dose–response relationship connects exposure amount with the type or frequency of effect.

Eutrophication

Eutrophication is nutrient enrichment, commonly involving nitrogen or phosphorus, that stimulates excessive biological growth.

Green chemistry

Green chemistry seeks to reduce hazard and waste at the design stage.

Primary pollutant

A primary pollutant is emitted directly from a source.

Secondary pollutant

A secondary pollutant forms in the atmosphere through reactions of emitted precursor substances.

Ch. 27 · Materials, Technology, and Modern Chemistry

Alloy

An alloy is a metallic material containing more than one element.

Anisotropy

This directional dependence is called anisotropy.

Composite

A composite combines two or more distinct material phases.

Doping

Doping intentionally introduces small amounts of selected atoms.

Glass-transition temperature

Below its glass-transition temperature, an amorphous polymer region is relatively rigid and glassy.

Hole

A missing electron in the valence states behaves as an effective positive charge carrier called a hole.

Life-cycle assessment

A life-cycle assessment examines impacts across extraction, refining, manufacturing, transportation, use, repair, reuse, recycling, and disposal.

Matrix

One phase is commonly the matrix, which surrounds and transfers load.

Nanomaterial

A nanomaterial has important structural features on the nanometer scale, commonly from about 1 to 100 nm.

Polycrystalline

Most engineering metals and ceramics are polycrystalline: they contain many small crystals called grains.

Reinforcement

Another is the reinforcement, which supplies strength or stiffness.

Smart materials

Smart materials respond to external conditions.

Strain

Strain is fractional change in length: ε=(Δ L)/(L_0).

Stress

Stress is force divided by cross-sectional area: σ=(F)/(A).

Yield strength

The yield strength marks the onset of significant plastic deformation in many materials.

Ch. 28 · Laboratory Safety, Equipment, and Technique

Hazard

A hazard is a source with the potential to cause harm.

Parallax error

Looking from above or below produces parallax error.

Risk

Risk combines the likelihood of an unwanted event with the severity of its consequences under the actual conditions.

SDS

A Safety Data Sheet, or SDS, uses a standard 16-section structure.

Waste segregation

Waste segregation keeps incompatible materials and wastes with different handling requirements in separate, labeled streams.

Ch. 29 · Cumulative Chemistry Problem-Solving

Error analysis

Error analysis names that first mistake and ties the repair to a specific rule, unit, relationship, or calculator entry.

Known quantities

The values, units, and species supplied by the problem are its known quantities, or known information.

Reasonableness check

A reasonableness check asks whether the unit, sign, scale, direction, chemical meaning, and reported precision agree with the situation.

Unit analysis

Unit analysis uses those cancellations to test the path before the calculator result is trusted.

Ch. 30 · Final Review: Chemistry as a Connected System

Acid–base chemistry

Acid–base chemistry follows proton transfer and hydronium concentration.

Atomic structure

Atomic structure connects proton identity and electron arrangement with elemental behavior.

Mole concept

The mole concept connects particle count with measurable mass.

Redox chemistry

Redox chemistry follows electron transfer and oxidation-number change.

Thermochemistry

Thermochemistry follows energy absorbed or released during change.

Glossary

Acid

A proton donor. In water, an acid increases hydronium concentration.

Acidemia

An arterial blood pH below the usual physiologic reference range.

Acidosis

A physiologic process that tends to lower blood pH.

Activation energy

The minimum energy barrier a reaction pathway must overcome.

Actual yield

The amount of product obtained in an experiment.

Alkalemia

An arterial blood pH above the usual physiologic reference range.

Alkalosis

A physiologic process that tends to raise blood pH.

Alpha decay

A nuclear change that emits a helium-4 nucleus, lowering mass number by 4 and atomic number by 2.

Anion

A negatively charged ion.

Anode

The electrode where oxidation occurs.

Atom

The smallest unit that retains an element’s chemical identity.

Atomic number

The number of protons in an atom’s nucleus.

Base

A proton acceptor. An Arrhenius base increases hydroxide concentration in water.

Beta-minus decay

A nuclear change in which a neutron becomes a proton while an electron and an antineutrino are emitted. Mass number stays constant and the daughter’s atomic number increases by 1.

Bioaccumulation

Buildup of a substance within one organism over time when intake exceeds elimination.

Biomagnification

Increasing concentration of a persistent substance across trophic levels in a food web.

Buffer

A mixture that resists large pH change when modest acid or base is added.

Catalyst

A substance that increases reaction rate through a lower-energy pathway and is regenerated.

Cathode

The electrode where reduction occurs.

Cation

A positively charged ion.

Chemical bond

An interaction that holds atoms together within a substance.

Chemical change

A change that produces substances with new chemical compositions.

Coefficient

A number placed before a formula to show relative amount in an equation.

Compound

A pure substance containing two or more elements chemically combined in fixed proportions.

Concentration

The amount of a specified component in a given amount of mixture or solution.

Conjugate pair

Two species related by gain or loss of one proton.

Covalent bond

A bond involving shared electron density between atoms.

Density

Mass per unit volume.

Dependent variable

The measured response in an investigation.

Dipole

A separation of partial positive and negative charge.

Dissociation

Separation of existing ions when an ionic substance dissolves.

Electrolyte

A substance that produces mobile ions and enables a solution to conduct electricity.

Electron

A negatively charged subatomic particle found in the electron cloud.

Electronegativity

An atom’s relative attraction for shared electrons in a bond.

Element

A substance whose atoms all have the same proton count.

Empirical formula

The lowest whole-number ratio of elements in a compound.

Endothermic

Absorbing heat into the system. Δ H is positive under the stated convention.

Endpoint

The observed signal used to stop a titration, chosen near equivalence.

Equilibrium

A dynamic state in which forward and reverse rates are equal.

Equivalence point

The point at which titration reactants have combined in the stoichiometric ratio.

Exothermic

Releasing heat from the system. Δ H is negative under the stated convention.

Exposure

Contact with a chemical or physical agent by a particular route, frequency, and duration. Radiation exposure does not necessarily mean radioactive material is present on the person or object.

Fission

A nuclear process in which a heavy nucleus splits into smaller nuclei and other particles.

Fusion

A nuclear process in which light nuclei combine to form a heavier nucleus.

Gamma radiation

High-energy electromagnetic radiation emitted by a nucleus. It carries no mass number or atomic number.

Half-life

The time required for half of a specified radioactive sample to decay.

Hydrate

A crystalline compound containing a fixed ratio of water molecules.

Hydrogen bond

A strong directional dipole attraction involving H bonded to N, O, or F and a nearby lone pair.

Hypothesis

A testable proposed explanation or prediction.

Independent variable

The factor deliberately changed in an investigation.

Intermolecular force

An attraction between separate particles or molecules.

Ion

An atom or bonded group with a net electric charge.

Ionic bond

Electrostatic attraction between oppositely charged ions.

Ionization

Formation of ions, often by reaction of a molecular substance with water.

Ionizing radiation

Radiation energetic enough to remove electrons from atoms or molecules.

Isotope

An atom with the same proton count as its element but a different neutron count.

Limiting reactant

The reactant consumed first according to stoichiometry, limiting product amount.

London dispersion force

Attraction caused by instantaneous and induced electron-distribution fluctuations.

Mass number

The total number of protons and neutrons in a particular nucleus.

Mixture

A physical combination of substances with variable composition.

Molar mass

Mass of one mole of specified entities, usually in grams per mole.

Molarity

Moles of solute per liter of solution.

Mole

The amount containing exactly 6.02214076 × 10^23 specified entities.

Molecular formula

The actual number of each type of atom in a molecule.

Molecule

A discrete, electrically neutral group of covalently bonded atoms.

Net ionic equation

An equation showing the species that undergo the chemical change, with spectators removed.

Neutron

An electrically neutral subatomic particle in the nucleus.

Nuclear reaction

A change in the composition or energy state of a nucleus.

Orbital

A quantum-mechanical description of an electron state and spatial probability distribution.

Oxidation

Loss of electrons or increase in oxidation number.

Oxidizing agent

A species that causes oxidation and is itself reduced.

Percent yield

Actual yield divided by theoretical yield, multiplied by 100.

Periodic trend

A recurring property pattern connected with position in the periodic table.

PH

A logarithmic measure related to hydrogen-ion activity. Introductory problems often use -.

Physical change

A change in form or state without a change in chemical identity.

Polyatomic ion

A covalently bonded group of atoms with an overall charge.

Precipitate

A solid formed from species in solution during a reaction.

Product

A substance formed by a chemical reaction.

Proton

A positively charged subatomic particle in the nucleus.

Radioactive contamination

Radioactive material present in an unintended place, such as on a surface, object, or person.

Radioisotope

A radioactive isotope with an unstable nucleus.

Reactant

A starting substance consumed or transformed in a reaction.

Reduction

Gain of electrons or decrease in oxidation number.

Scientific law

A concise description of a repeatedly observed relationship.

Scientific theory

A broad, evidence-supported explanatory framework.

Solute

A solution component considered dissolved in a solvent.

Solution

A homogeneous mixture at the scale being considered.

Solvent

The solution component that serves as the dissolving medium.

Spectator ion

An ion that appears unchanged on both sides of an ionic equation.

Stoichiometry

Quantitative relationships among substances in a balanced chemical equation.

Strong acid

An acid that ionizes extensively in water under the stated conditions.

Subscript

A small number in a formula that shows relative atom or ion count.

Theoretical yield

The maximum product predicted from stoichiometry and the limiting reactant.

Valence electron

An outer electron that strongly influences bonding and chemical behavior.

81 more chemistry terms

Terms from the grade-level chemistry deck that are not already listed above, grouped by topic.

Acids, Bases, and Electrochemistry

Acid-base indicator

A dye whose color changes over a known pH range, used to signal a change in acidity. Phenolphthalein is colourless in acid and pink above about pH 8.3.

Bronsted-Lowry base

A species that accepts a proton, that is an H+ ion, from another species during a reaction. Ammonia is one, since NH3 takes a proton from water to become NH4+.

Burette

A long graduated glass tube with a tap, used to deliver and measure variable volumes accurately during a titration. Read the bottom of the meniscus at eye level, and record the volume delivered.

Concentrated acid

An acid solution containing a large amount of acid per liter, which is a statement about amount, not about strength. Concentrated acetic acid is still a weak acid because it ionizes only partly.

Conjugate acid-base pair

Two species that differ by exactly one proton, one formed from the other in an acid-base reaction. HCl and Cl- are such a pair, and so are H2O and OH-.

End point

The moment in a titration when the indicator changes color and you stop adding titrant. It is an observation that only approximates the equivalence point, so choose an indicator that changes near it.

Half-reaction

One side of a redox process written on its own, showing either the electrons lost or the electrons gained. Balancing the two half-reactions so the electrons cancel gives the full redox equation.

Hydronium ion

The H3O+ ion formed when a proton attaches to a water molecule, and the species that makes a solution acidic. Chemists write H+ as shorthand, but in water it is really H3O+.

Neutralization

The reaction of an acid with a base to produce water and a salt. The final solution is pH 7 only for a strong acid with a strong base, since a weak acid with a strong base ends up basic.

Applied Chemistry and the Lab

Acid deposition

The fall of acidic rain, snow or dry particles caused by sulfur and nitrogen oxides reacting with water in the air. It damages lakes, soils and limestone buildings far from the source.

Active ingredient

The component of a medicine or product that produces the intended effect, listed with its strength on the label. A tablet marked 500 mg paracetamol contains that mass of the active ingredient.

ATP

Adenosine triphosphate, the molecule cells use to move energy from one process to another. Breaking off one phosphate group releases energy that drives muscle contraction and other cell work.

Disinfectant

A chemical that kills most microbes on surfaces, working more thoroughly than a sanitiser and needing a stated contact time. Never mix bleach with ammonia or acids, as toxic gases form.

Fume hood

A ventilated enclosure that draws harmful vapors away from you and out of the room. Work well inside the opening with the sash low, and check the airflow before starting.

Hierarchy of controls

The ranked order for reducing risk: eliminate the hazard, substitute a safer one, use engineering controls, then rules, and last protective equipment. Higher steps protect everyone, not just the careful.

Personal protective equipment

Gear worn to reduce exposure when hazards remain, such as splash goggles, a lab coat and suitable gloves. It is the last line of defence, so it never replaces safer methods or ventilation.

Safety data sheet

A standard document giving a chemical’s hazards, handling rules, storage, first aid and disposal advice. Read the relevant sections before you open the bottle, not after something goes wrong.

Semiconductor

A material whose electrical conductivity sits between that of a metal and an insulator and can be controlled. Silicon with tiny added impurities is the basis of chips and solar cells.

Structural isomer

One of two or more compounds with the same molecular formula but different arrangements of atoms. Butane and 2-methylpropane are both C4H10, yet they boil at different temperatures.

Surfactant

A molecule with a water-loving head and an oil-loving tail that lets oil and water mix. Soaps and detergents are surfactants, surrounding greasy dirt so water can rinse it away.

Tare

Zeroing a balance with the empty container in place so it reports only the mass added afterwards. Tare with the weighing boat on the pan, then add solid until the display shows the mass you want.

Bonding, Shape, and Forces

Crystal lattice

The repeating three-dimensional pattern in which ions pack so every ion is surrounded by opposite charges. It explains why ionic solids are hard and melt high.

Dipole-dipole attraction

The attraction between the positive end of one polar molecule and the negative end of another. It raises boiling points above those of similar nonpolar substances.

Lewis structure

A drawing of a molecule showing every bonding pair as a line and every lone pair as two dots. In H2O the oxygen has two bonds and two lone pairs.

Like dissolves like

The guideline that polar and ionic solutes dissolve in polar solvents while nonpolar solutes dissolve in nonpolar solvents. Oil will not mix into water.

Lone pair

A pair of valence electrons that stays on one atom instead of being shared. Ammonia, NH3, has three bonding pairs and one lone pair on the nitrogen.

Metallic bonding

Metal cations held together by electrons that move freely through the whole structure. That loose sea of electrons explains conduction and bending without cracking.

Network covalent solid

A solid in which atoms are joined by covalent bonds through one continuous network rather than separate molecules. Diamond and SiO2 melt at very high temperatures.

Nonpolar covalent bond

A bond in which both atoms pull the shared electrons about equally, so no partial charges build up. The Cl-Cl bond in Cl2 shares its pair evenly.

Polar molecule

A molecule whose bond dipoles do not cancel, so it has an overall positive end and negative end. CO2 has polar bonds yet is nonpolar because they cancel.

VSEPR theory

The idea that electron groups around a central atom push apart as far as possible, which sets the molecule’s shape. Four electron groups give a tetrahedral arrangement.

Energy, Rates, and Equilibrium

Calorimeter constant

The energy needed to warm the calorimeter itself by one degree Celsius. Ignoring it makes a measured reaction enthalpy come out smaller than the true value.

Endothermic reaction

A reaction that takes in energy from the surroundings, so the surroundings cool and the enthalpy change is positive. This is why an instant cold pack feels cold.

Enthalpy change

The heat taken in or given out by a reaction at constant pressure, written as delta H in kJ/mol. A negative value means energy left the system.

Exothermic reaction

A reaction that releases energy to the surroundings, so the surroundings warm up and the enthalpy change is negative. Burning methane is a familiar example.

Heat of fusion

The energy needed to melt a given amount of a solid at its melting point, with no temperature change. The same energy is given out again when the liquid freezes.

Heat of vaporization

The energy needed to turn a given amount of liquid into gas at its boiling point. For any one substance it is larger than the heat of fusion.

Heating curve

A graph of temperature against energy added as a substance is heated. The flat sections are phase changes, where energy separates particles instead of raising temperature.

Le Chatelier’s principle

The rule that a system at equilibrium answers a disturbance by shifting in the direction that partly cancels it. Adding more reactant shifts the position toward products.

Molar enthalpy of reaction

The energy change per mole of a named substance reacting, reported in kJ/mol. Divide the measured joules by the moles that actually reacted.

Specific heat capacity

The energy needed to raise one gram of a substance by one degree Celsius. Water’s large value of 4.18 J per gram per degree means it heats and cools slowly.

Foundations, Math, and Measurement

Accuracy

How close a measured value is to the true or accepted value. A balance reading 9.8 g for a mass known to be 10.0 g is fairly accurate.

Metric prefix

A word part placed in front of a unit that multiplies it by a power of ten. Kilo means 1000, centi means one hundredth, and milli means one thousandth.

Precision

How closely repeated measurements agree with each other, and how finely an instrument reads. Readings can be very precise and still all be wrong if the tool is off.

Qualitative data

Observations that describe a quality without a number, such as color, odor, or whether a gas forms. The blue solution turned green is qualitative.

Quantitative data

Observations recorded as a number with a unit, obtained by measuring. A mass of 12.4 g or a volume of 25.0 mL is quantitative data.

Scientific notation

A way of writing a number as a value between 1 and 10 multiplied by a power of ten. 0.00045 becomes 4.5 x 10^-4 and 6200 becomes 6.2 x 10^3.

SI base unit

One of the agreed fundamental units of the metric system, such as the meter, kilogram, second, and kelvin. Every other science unit is built from these.

Slope

The steepness of a straight line on a graph, found as rise over run, the change in y divided by the change in x. On a mass against volume graph the slope is density.

Uncertainty

The range in which the true value of a measurement probably lies, set by the limits of the instrument. A ruler marked in mm gives about plus or minus 0.5 mm.

Weight

The force gravity pulls on an object with, measured in newtons, so it changes where gravity is different. That same book weighs about six times less on the Moon.

Gases, Solutions, and States

Avogadro’s law

At the same temperature and pressure, equal volumes of any gas contain equal numbers of particles, so volume is proportional to moles. Adding more gas to a flexible balloon makes it bigger.

Boyle’s law

For a fixed amount of gas at constant temperature, pressure and volume are inversely proportional. Squeeze a syringe to half its volume and the pressure inside roughly doubles.

Charles’s law

For a fixed amount of gas at constant pressure, volume is directly proportional to absolute temperature. A balloon taken outdoors on a cold day shrinks because the kelvin temperature falls.

Colloid

A mixture whose dispersed particles are too large to be dissolved but too small to settle out. Milk and fog are colloids, and they scatter a light beam, unlike a true solution.

Gas pressure

The force that gas particles exert per unit of area when they collide with the walls of their container. More frequent or harder collisions mean higher pressure, measured in atm or kPa.

Ideal gas law

The relationship PV = nRT, which links pressure, volume, moles and absolute temperature through the gas constant R. Use it when you know three of the four quantities and want the fourth.

Kelvin scale

An absolute temperature scale whose zero point is the temperature at which particle motion energy is minimal. Add 273 to a Celsius value, so 25 C is 298 K, and always use kelvins in gas laws.

Partial pressure

The pressure one gas in a mixture would exert if it alone filled the container. By Dalton’s law the partial pressures add up to the total, so dry air is mostly the N2 and O2 contributions.

Phase diagram

A graph of pressure against temperature showing which state a substance is in and where two states coexist. The three curves meet at the triple point, where solid, liquid and gas all coexist.

Saturated solution

A solution holding as much dissolved solute as it can at that temperature, with dissolving and crystallising in balance. Saturated does not mean concentrated, since a barely soluble salt saturates at a low concentration.

Supersaturated solution

An unstable solution holding more dissolved solute than its normal solubility, usually made by cooling a hot saturated solution slowly. A seed crystal makes the excess crystallize at once.

Matter, Atoms, and Periodic Trends

Average atomic mass

The weighted mean mass of an element’s natural isotopes, listed on the periodic table in g/mol. Chlorine’s 35.45 is not the mass of any single chlorine atom.

Electron configuration

A notation listing which orbitals an atom’s electrons occupy, filled from the lowest energy upward. Oxygen is written 1s2 2s2 2p4.

Energy level

One of the allowed energies an electron in an atom may have, with no values in between. Dropping to a lower level releases a photon of a fixed energy.

Group

A vertical column of the periodic table whose elements share the same number of valence electrons and behave alike. Group 1 metals all react with water.

Heterogeneous mixture

A mixture whose makeup is not uniform, so different samples of it are not the same. Sand stirred into water or a tossed salad shows visibly separate parts.

Ionic radius

The size of an atom once it has become an ion. Cations are smaller than the atoms they came from, while anions are larger because extra electrons repel.

Ionization energy

The energy needed to pull the most loosely held electron away from a neutral gaseous atom. It rises across a period because the nucleus grips more tightly.

Moles, Formulas, and Stoichiometry

Anhydrous

Describes the solid that remains after all water of hydration has been driven off by heating. Heating blue CuSO4 . 5H2O leaves white anhydrous CuSO4.

Avogadro’s number

The number of representative particles in exactly one mole, 6.022 x 10^23 per mole. Divide a count of atoms or molecules by it to get moles.

Dimensional analysis

Solving by chaining conversion factors so units cancel and only the target unit survives. If the final unit is wrong, the setup is wrong even when the arithmetic is fine.

Empirical formula mass

The mass in g/mol of one empirical formula unit. Dividing the molar mass by it gives the whole number that scales the empirical formula up to the molecular formula.

Excess reactant

The reactant that is still left over once the limiting reactant is gone. Its leftover amount is the starting amount minus the amount that reacted.

Mass-to-mass stoichiometry

A calculation that turns grams of one substance into moles, applies the mole ratio, then converts back to grams of another. Molar mass is needed at both ends.

Mole ratio

A conversion factor built from the coefficients of a balanced equation, linking moles of one substance to moles of another. In N2 + 3H2 -> 2NH3, H2 to NH3 is 3 to 2.

Percent composition

The share of a compound’s total mass supplied by each element, found as element mass divided by total mass, times 100. Water is about 11.2 percent hydrogen by mass.

Representative particle

The kind of entity being counted for a given substance, such as an atom, a molecule, or a formula unit. For NaCl the particle counted is the formula unit.

Water of hydration

Water molecules locked in fixed proportion inside a hydrate’s crystal. Their mass counts in the hydrate’s molar mass and is lost when the sample is heated to constant mass.

Reactions and Aqueous Chemistry

Balanced chemical equation

An equation whose coefficients make each element appear the same number of times on both sides. Only coefficients may be adjusted, never the subscripts inside a formula.

Neutralization reaction

A reaction between an acid and a base that produces water plus a salt, as in HCl + NaOH -> NaCl + H2O. The net change is usually H+ joining OH- to make H2O.