THE LESSON LIBRARY / CHEMISTRY
Chemistry, explored.
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Magnetic separation Learning Model
Explore the free magnetic separation chemistry station. Read the model assumptions, make a prediction and compare the numerical and visual results.
Explore lesson ChemistryLessonMagnetic Susceptibility and Its Measurement
Counting unpaired electrons predicts a possible moment, but experiment measures a response to a magnetic field. Magnetic susceptibility connects these ideas. It can be measured…
Explore lesson ChemistryLessonMagnetism
Hold a magnet near a paper clip and it jumps across the gap. Hold it near a copper coin, an aluminium can or a gold ring and nothing happens. Being attracted to a magnet is a…
Explore lesson ChemistryLessonMagnetism and Electron Configuration
The same d-electron count can give different numbers of unpaired electrons when ligands change the energy gap between d levels. Magnetic behaviour provides evidence about that…
Explore lesson ChemistryLessonMagnetism from Unpaired Electrons
MO diagrams can predict whether a molecule has unpaired electrons. Ground-state O₂ has two and is paramagnetic, while N₂ has paired valence electrons and is diamagnetic. The…
Explore lesson ChemistryLessonMagnetism of Coordination Compounds
Magnetic measurements reveal something about a complex's electronic structure. Unpaired electrons usually make a complex paramagnetic; all-paired electron configurations are…
Explore lesson ChemistryLessonMagnetism of Lanthanide Ions
The spin-only formula is often a useful first approximation for 3d complexes because ligand fields partly quench orbital angular momentum. Lanthanide 4f electrons behave…
Explore lesson ChemistryLessonMagnetism, Colour and Spin State Together
Magnetism reports how many electrons remain unpaired; optical absorption probes differences between electronic energy levels. Used together, they can support a ligand-field model…
Explore lesson ChemistryLessonMain Groups and Valence Patterns
Fluorine and chlorine have different total electron counts, but their neutral outer-shell configurations both end in ns²np⁵. That repeated seven-electron pattern helps explain…
Explore lesson ChemistryCollectionMain-Group and Transition-Metal Chemistry
Study Main-Group and Transition-Metal Chemistry with 70 free lessons, worked examples, and answered practice questions.
Explore lesson ChemistryLessonMain-Group and Transition-Metal Chemistry: Unit Review
Inorganic chemistry is most useful when its themes work together. Acid–base definitions explain hydrolysis and oxide behaviour. Periodic trends help predict the chemistry of…
Explore lesson ChemistryLessonMain-Group Elements and Transition Elements
The periodic table can be split into two broad regions. On the left and right stand the main-group elements: tall columns whose members follow clear, simple patterns. In the…
Explore lesson ChemistryLessonMaking Water Safe to Drink
Water from rivers, reservoirs and wells may look clean, but it can contain mud, leaves, dissolved chemicals and — most dangerously — bacteria and viruses that cause diseases such…
Explore lesson ChemistryLessonMalleability and Ductility — Matter and its Properties
Aluminium foil, copper wire, gold leaf and steel car panels all exist because metals can be reshaped without breaking. Two closely related physical properties describe this…
Explore lesson ChemistryLessonMalleability and Ductility — Metals, Reactivity Series and Metallurgy Basics
Many metals can be hammered into sheets or drawn into wires. These processes both require permanent shape change without immediate fracture, but they apply different kinds of…
Explore lesson ChemistryLessonManipulating Fischer Projections
A Fischer projection is a flat code for a three-dimensional object, and like any code it only works if it is handled by strict rules. Some movements of the drawing on the page…
Explore lesson ChemistryLessonMany-Electron Wavefunctions and Antisymmetry
One-electron molecular orbitals are convenient building blocks, but real molecules contain multiple identical electrons. Exchanging the labels of two electrons cannot produce a…
Explore lesson ChemistryLessonMapping the p-Block
The p-block occupies the right-hand six columns of the long-form periodic table, groups 13 through 18. Its elements range from metals such as aluminium to nonmetals such as…
Explore lesson ChemistryLessonMarcus Theory of Electron Transfer
Butler–Volmer describes a roughly exponential response to potential when an activation barrier changes approximately linearly with driving force. Marcus theory asks where that…
Explore lesson ChemistryLessonMarcus–Hush–Chidsey Kinetics at Metal Electrodes
The previous page treated electron transfer between two specified states. A metal electrode is different: it offers many electronic states above and below a Fermi level. An…
Explore lesson ChemistryLessonMarkovnikov Orientation
An unsymmetrical alkene can accept an unsymmetrical reagent in more than one orientation. Markovnikov's rule summarizes a frequent polar-addition outcome, especially for hydrogen…
Explore lesson ChemistryLessonMass and Weight
In everyday speech people say "I weigh 50 kilograms", but scientists would say "my mass is 50 kilograms". Mass and weight are related but they are not the same quantity. An…
Explore lesson ChemistryLessonMass Balance across Linked Steps
Sequential mixing, evaporation and transfer problems are easy to mishandle if only the total solution mass is tracked. A component table keeps solute and solvent separate at…
Explore lesson ChemistryLessonMass Balance in Aqueous Systems
When you dissolve 0.10 mol of ethanoic acid in a litre of water, you do not end up with 0.10 mol dm⁻³ of CH₃COOH molecules. Some of the acid becomes ethanoate ions. Yet nothing…
Explore lesson ChemistryLessonMass Balance in Ionic Equilibrium
Equilibrium reactions redistribute atoms; they do not create them. A component mass balance counts a selected chemical component across every dissolved form that contains it.…
Explore lesson ChemistryLessonMass Conservation as a Calculation Check
A product can weigh more than one starting material or a heated solid can weigh less than before. Neither observation alone disproves mass conservation. A meaningful check adds…
Explore lesson ChemistryLessonMass Defect and Nuclear Binding Energy
Weigh a helium-4 atom and compare it with the combined mass of two hydrogen atoms and two neutrons. The helium atom is lighter by about 0.8%. That missing mass is not lost: it…
Explore lesson ChemistryLessonMass Fraction of a Solute
Mass fraction specifies what part of a solution's mass belongs to a chosen solute. The denominator is the mass of the *whole liquid solution*, including solvent and all dissolved…
Explore lesson ChemistryLessonMass Number
An isotope name such as carbon-14 or sodium-23 includes a whole number. That number counts the nucleons in its nucleus. It does not count electrons, and it is not a decimal…
Explore lesson ChemistryLessonMass Number and Nucleon Counting
An atom's mass number is a count, not a weighing result. It is the number of protons plus neutrons in a particular nucleus. Carbon-12 has A = 12 because its nucleus contains six…
Explore lesson ChemistryLessonMass Number Is Not Isotopic Mass
Chlorine-35 has mass number 35, but its measured atomic mass is not exactly 35.000000 u. The first number counts nucleons; the second measures the mass of an actual atom on the…
Explore lesson ChemistryLessonMass Number Versus Relative Atomic Mass
A periodic table may list chlorine near 35.45, yet no chlorine nucleus contains a fractional nucleon. The apparent puzzle comes from confusing two quantities. Mass number…
Explore lesson ChemistryLessonMass of an Element Within a Compound
A compound's mass is shared among its constituent elements. If the amount or mass of the compound is known, its formula tells how many moles of each element's atoms are…
Explore lesson ChemistryLessonMass per Volume Concentration
Mass per volume concentration compares a named solute's mass with the final liquid volume. It is convenient when a sample volume is measured directly and the solute amount is…
Explore lesson ChemistryLessonMass Percent Concentration
Mass percent is a familiar way to report a component's share of a solution, but “percent” needs its basis. A 10% by mass salt solution contains 10 g salt per 100 g total…
Explore lesson ChemistryLessonMass Percent in Solutions
A solution contains at least a solute and a solvent. Mass percent describes how much of the entire solution's mass belongs to the named solute. The denominator is the final…
Explore lesson ChemistryLessonMass Percentage and Parts per Million
Mass percentage and parts per million describe how much of a solution's mass comes from a named component. They are useful when preparation is based on weighing and when a trace…
Explore lesson ChemistryLabMass spectrometry
A mass spectrum: the molecule breaks into charged fragments, sorted by mass.
Explore lesson ChemistryLessonMass to Number of Particles
A balance measures grams, but a question may ask how many molecules or formula units those grams contain. Molar mass converts grams to moles; the Avogadro constant converts moles…
Explore lesson ChemistryLessonMass Transport in Electrolysis
An electrode can react only with species that reach its interface. Even a fast electron-transfer reaction slows if reactant delivery cannot keep up with current demand. Mass…
Explore lesson ChemistryLessonMass Transport to Electrodes
An electrode can react only with species that reach its surface. Once electron transfer becomes fast, supplying reactant may be the bottleneck. Diffusion, migration and…
Explore lesson ChemistryLessonMass-to-Charge Ratio and the Mass Spectrum
A mass spectrum looks like a bar chart: a row of thin vertical lines of different heights standing on a horizontal axis. To read one you need to understand exactly what each axis…
Explore lesson ChemistryLessonMass-to-Mass Stoichiometry
Reaction coefficients connect particle amounts, while laboratory balances measure mass. To predict product grams from reactant grams, move through moles on both sides of the…
Explore lesson ChemistryLessonMass–Mole Conversions in Reactions
A balance reports grams, while a balanced reaction reports particle and mole ratios. Mass–mole conversion connects these descriptions. It is the first calculation in many…
Explore lesson ChemistryLessonMass: The Amount of Matter
A brick feels heavier than a sponge of the same size because it contains more matter. The quantity that tells us "how much matter" is mass. Mass is one of the most important…
Explore lesson ChemistryLessonMass: The Kilogram
Every SI base unit has a simple name — metre, second, mole — except one. The base unit of mass is the kilo-gram, which already contains the prefix "kilo", meaning a thousand.…
Explore lesson ChemistryLessonMasses of Formulae with Brackets
Some formulae contain brackets, such as Ca(OH)₂ for calcium hydroxide (slaked lime) and Mg(NO₃)₂ for magnesium nitrate. Brackets are a compact way of saying "this group of atoms…
Explore lesson ChemistryLessonMasses of Subatomic Particles
Almost all atomic mass lies in the nucleus, even though the electron region occupies most of the atom's volume. This follows from the masses of the constituent particles.…
Explore lesson ChemistryLessonMatching Techniques to Structural Questions
Faced with an unknown compound, a chemist asks a series of questions. How heavy is the molecule? Which functional groups does it contain? How are the carbon and hydrogen atoms…
Explore lesson ChemistryLessonMaterials Chemistry Terms
Materials chemistry connects composition and structure to electrical, mechanical, optical and chemical behavior. A chemical formula alone may not identify a material's useful…
Explore lesson ChemistryLessonMaterials Screening and Scale-Up
A record-setting laboratory cell can be a useful discovery without being a practical product. A few milligrams of powder, a tiny illuminated pixel or a carefully selected…
Explore lesson ChemistryCollectionMatter and its Properties
Study Matter and its Properties with 50 free lessons, worked examples, and answered practice questions.
Explore lesson ChemistryLessonMatter and Its Properties: Unit Review
This unit began with a simple question — what is matter? — and built up a set of tools for describing it: mass, volume, density, physical and chemical properties, and finally the…
Explore lesson ChemistryLessonMatter and Measurement Map
The first chemistry map begins with matter that can be observed and measured. A beaker contains particles, but a balance reports mass, a thermometer reports temperature and a…
Explore lesson ChemistryLessonMatter and Measurement Practice
Measurement and matter classification are prerequisites for almost every later chemistry calculation. A clear liquid can be a mixture; a two-phase beaker can contain one…
Explore lesson ChemistryLessonMatter and Substance Terms
Matter vocabulary is easy to blur because a sample can be described in several ways at once. A glass of salt water is matter, a mixture, a single visible liquid phase at ordinary…
Explore lesson ChemistryLessonMatter and Things That Are Not Matter
Some things in our world are obviously real but are not made of matter at all. A rainbow, a musical note, the warmth of a fire and a good idea all exist, yet none of them can be…
Explore lesson ChemistryLessonMatter Waves and de Broglie Wavelength
Light has wave properties yet transfers energy in photon quanta. De Broglie proposed a complementary idea: moving material particles can have a wavelength related to their…
Explore lesson ChemistryLessonMaxwell–Boltzmann Speed Distribution
Gas molecules at one temperature do not all move at one speed. Some are slow, many lie near a characteristic range and a smaller fraction move much faster. The Maxwell–Boltzmann…
Explore lesson ChemistryLessonMean Ionic Activity Coefficients
A salt dissociates into cations and anions, but a macroscopic solution cannot gain just one type of charge without an accompanying electrical effect. Thermodynamic measurements…
Explore lesson ChemistryLessonMean Radius and Expectation Values in Hydrogen
The most probable radius picks out the single peak of the radial distribution, but many measurable properties depend on averages taken over the whole electron cloud. The average…
Explore lesson ChemistryLessonMean, Range and Repeatability
A table of ten repeated readings is hard to take in at a glance. Scientists summarise such data with two simple numbers: the mean, which gives a single best estimate, and the…
Explore lesson ChemistryLessonMean, Standard Deviation and Relative Standard Deviation
Replicate analytical results rarely agree exactly. Their mean estimates a central value, and their standard deviation describes spread under the stated repeat conditions.…
Explore lesson ChemistryLabMeasurement and precision
Repeated readings land on a target: the centre is the true value. You see the difference between accuracy and precision.
Explore lesson ChemistryLessonMeasurement and Unit Terms
“The mass is 5.20” is incomplete; 5.20 grams and 5.20 kilograms differ by a factor of one thousand. Measurement language includes the quantity, its numerical value, a unit, the…
Explore lesson ChemistryLessonMeasurement in the Chemistry Laboratory
A chemistry laboratory contains many ways to measure the same quantity. You could measure 25 cm³ of solution with a beaker, a measuring cylinder, a burette or a pipette — but the…
Explore lesson ChemistryLessonMeasurement Traceability
When two laboratories report different concentrations for the same sample, the question is not merely which instrument is newer. Each result depends on standards, calibration…
Explore lesson ChemistryCollectionMeasurement, Units and SI
Study Measurement, Units and SI with 40 free lessons, worked examples, and answered practice questions.
Explore lesson ChemistryLessonMeasurement, Units and SI: Unit Review
This unit has built a toolkit for dealing with numbers in science. Every measurement needs a value and a unit; units must be standard and scalable; values must be written with…
Explore lesson ChemistryLessonMeasuring Amounts Safely in the Laboratory
A mole calculation is only as reliable as the mass and formula entered into it. A laboratory balance measures grams; it does not count molecules directly. Careful weighing…
Explore lesson ChemistryLessonMeasuring Greenness: Why Yield Is Not Enough
Chemists often judge a reaction by percentage yield. Yield matters: a low-yielding step consumes more starting material and usually complicates purification. Yet an 90% yield can…
Explore lesson ChemistryLessonMeasuring Instruments and Their Resolution
A kitchen scale and a laboratory balance both measure mass, but they tell you very different things. The kitchen scale might say 250 g; the laboratory balance might say 250.47 g.…
Explore lesson ChemistryLessonMeasuring Mass with a Balance
Almost every chemistry experiment begins with measuring out a substance, and most of the time that means using a balance. A careful measurement gives reliable results; a careless…
Explore lesson ChemistryLessonMeasuring Molar Mass: Colligative and End-Group Methods
Some polymer measurements respond to how many molecules are present rather than how much mass each contributes. Osmotic pressure and end-group analysis therefore naturally…
Explore lesson ChemistryLessonMeasuring Molar Mass: Light Scattering and Viscometry
Two important polymer-solution methods respond strongly to chain size. Static light scattering estimates weight-average molar mass, while dilute-solution viscometry measures how…
Explore lesson ChemistryLessonMeasuring Particle-Size Distributions
A nanoparticle batch almost never contains one exact diameter. “The size is 10 nm” hides the width, shape and weighting of a distribution. Counting individual cores by microscopy…
Explore lesson ChemistryLessonMeasuring pH with Universal Indicator and pH Meters
Knowing the idea of pH is one thing; measuring it reliably is another. A gardener checking soil, a nurse testing urine and an analyst monitoring river water all need a pH value…
Explore lesson ChemistryLessonMeasuring Photochemical Quantum Yields
A product count becomes a photochemical quantum yield only after the absorbed photon count is known. Measuring lamp electrical power is not enough: a source has a spectrum…
Explore lesson ChemistryLessonMeasuring Surface Area by Gas Adsorption
Two powders with the same mass can present vastly different amounts of surface to a gas. Porous catalyst supports often have hundreds of square metres of accessible area per…
Explore lesson ChemistryLessonMeasuring Tg
T_g is inferred from a change in material response, so different experiments can quote slightly different values. Calorimetry detects a heat-capacity change, dilatometry a change…
Explore lesson ChemistryLessonMeasuring the Volume of a Liquid
Liquids take the shape of their container, so their volume is measured by pouring them into apparatus with a marked scale. The most common tool in school laboratories is the…
Explore lesson ChemistryLessonMechanism Evidence and Problem Solving
A curved-arrow mechanism is a proposal for how a reaction occurs, not a fact established by a tidy drawing. Experiments can test its steps. Rate laws reveal which concentrations…
Explore lesson ChemistryLabMechanism player
Step through a reaction mechanism in 3D with curved arrows and an energy profile.
Explore lesson ChemistryLessonMechanism Steps and Energy Profiles
A balanced reaction tells us starting and ending substances, not how the reaction travels between them. A mechanism proposes elementary steps, and an energy profile depicts their…
Explore lesson ChemistryLessonMechanistic Tools for Organometallic Catalysis
A catalytic cycle drawn on paper is a hypothesis about unseen molecules. Spectra can identify some species, kinetics can reveal concentration dependencies, isotope labels can…
Explore lesson ChemistryLessonMedical Tracers
A medical tracer links chemistry to nuclear detection. A molecule carrying a radioactive isotope can follow a biological process, while emitted radiation allows an instrument to…
Explore lesson ChemistryLessonMelting
An ice lolly drips on a hot day, butter softens in a warm pan and a chocolate bar turns sticky in a pocket. All three are examples of melting: a solid turning into a liquid.…
Explore lesson ChemistryLessonMelting and Boiling Points as a Test of Purity
When a chemist makes a new medicine, one of the first questions is simple: is it pure? A tiny amount of an unwanted substance could make a drug less effective or even harmful.…
Explore lesson ChemistryLessonMelting and Boiling Points as Tests of Purity
In everyday language, "pure" orange juice means juice with nothing added. In chemistry, pure has a stricter meaning: a sample containing only one substance. Chemists who make…
Explore lesson ChemistryLessonMelting Point — Matter and its Properties
Ice melts at 0 °C, chocolate melts in your hand, and iron needs a blast furnace at over 1500 °C. The temperature at which a solid turns into a liquid is its melting point. It is…
Explore lesson ChemistryLessonMelting Point — States of Matter: Particle Model
Ice always melts at 0 °C, whether it is a single cube or an iceberg. Pure gold always melts at 1064 °C. Every pure solid has its own melting point, a fixed temperature at which…
Explore lesson ChemistryLessonMembrane Cells and Ion-Selective Separation
The chlor-alkali cell makes substances that should be collected separately. Chlorine forms near the anode, while hydrogen and hydroxide form near the cathode. A cation-exchange…
Explore lesson ChemistryLessonMendeleev's Periodic Classification
Mendeleev's periodic classification was powerful because it did more than tidy a list. It put many known elements into recurring families and left places for elements that had…
Explore lesson ChemistryLessonMendeleev's Periodic Table
In 1869 the Russian chemist Dmitri Mendeleev produced a table of the elements that changed chemistry. Others had noticed patterns, but Mendeleev did something bolder: he trusted…
Explore lesson ChemistryLessonMendeleev's Predictions Revisited
Mendeleev did not merely arrange known elements into a tidy chart. He left gaps where the repeating pattern suggested undiscovered elements and predicted their approximate…
Explore lesson ChemistryLessonMeso Compounds — Organic Conversions, Isomerism and Reasoning
Four different groups on a tetrahedral carbon usually warn of chirality. Yet a molecule with two such centres can be achiral if its two halves have a suitable symmetry. This is a…
Explore lesson ChemistryLessonMeso Compounds — Stereochemistry and Conformational Analysis
It is tempting to believe that a molecule containing stereocentres must be chiral. Meso compounds prove otherwise. They contain two or more stereocentres, yet they are…
Explore lesson ChemistryLessonMetal Alkyls and β-Hydrogen Stability
For much of the twentieth century, simple transition-metal alkyls such as tetraethyltitanium were thought to be intrinsically unstable, because attempts to make them usually…
Explore lesson ChemistryLessonMetal Binding Affinity and Selectivity
A protein site does not simply "choose" its metal. Every metal ion in the cell competes with protons, with other metals and with thousands of other ligands for the same donor…
Explore lesson ChemistryLessonMetal Carbenes and Carbynes
A metal alkyl has a metal–carbon single bond, but organometallic carbon ligands can form stronger multiple-bond interactions. Metal carbenes, commonly written M=C(R)R′, appear in…
Explore lesson ChemistryLessonMetal Carbonyl Bonding
Carbon monoxide binds many transition metals through carbon. Its bond to the metal is not just a one-way donation: CO donates electron density to the metal and accepts electron…
Explore lesson ChemistryLessonMetal Chelation in Biology and Medicine
When two ligands compete for the same metal ion, the one that wins is not always the one with the most donor atoms or the highest formal binding constant. It is the one that…
Explore lesson ChemistryLessonMetal Dependence of Δ
The spectrochemical series ranks ligands only within a controlled comparison. Even if the ligand remains unchanged, the metal can change the splitting markedly. A higher…
Explore lesson ChemistryLabMetal displacement
A more reactive metal pushes a less reactive metal out of its salt solution by giving it electrons.
Explore lesson ChemistryLabMetal extraction principles
An Ellingham diagram shows when carbon or CO can reduce a metal oxide to the metal.
Explore lesson ChemistryLessonMetal Hydrides
Hydrogen is the smallest ligand, yet metal–hydrogen bonds sit at the centre of hydrogenation, hydroformylation, alkene isomerisation and many reductions in industry and in…
Explore lesson ChemistryLessonMetal Ions in Living Systems
Life uses organic molecules for most of its structure, yet many crucial tasks rely on inorganic ions. Metals can hold a protein in a useful shape, polarize a substrate, transfer…
Explore lesson ChemistryLessonMetal Nanoparticle Plasmons
Some metal nanoparticles show vivid colors even though their material is a familiar shiny bulk metal. Incident light can drive the particle's mobile electrons to oscillate…
Explore lesson ChemistryLessonMetal Nanoparticles and Surface Plasmons
Gold metal looks yellow as a bulk solid, yet a dispersed gold nanoparticle sample can appear red or purple. The origin is usually not the semiconductor band-gap mechanism of the…
Explore lesson ChemistryLessonMetal Oxidation State in Complexes
A complex ion's charge is not usually the same as the central metal's oxidation state. Bound ligands contribute their own formal charges. The reliable calculation is a charge…
Explore lesson ChemistryLessonMetal Oxides Are Basic
Many metal oxides behave as bases: they react with acids to form a salt and water. Some also react with water to give hydroxides and alkaline solutions. This is a broad pattern…
Explore lesson ChemistryLessonMetal Oxides as Extraction Intermediates
An extraction route may convert a carbonate or sulfide mineral to an oxide before producing metal. The oxide is an intermediate: its metal atoms are still chemically combined…
Explore lesson ChemistryLessonMetal Recycling as Re-Extraction Avoidance
Recycling returns metal atoms from used products to new service. Because those atoms are already in metallic or alloy form, recycling can avoid some mining, ore concentration and…
Explore lesson ChemistryLessonMetal Speciation and Toxicity in Water
A water report may list “total lead” or “total mercury,” but neither number describes a single chemical particle. Dissolved ions, complexes, precipitates and particle-bound forms…
Explore lesson ChemistryLessonMetal Toxicity and Mis-Metallation
Toxicity is not a special property of "poisonous" elements alone. Even essential metals become toxic when they occupy the wrong site, and highly toxic metals such as mercury…
Explore lesson ChemistryLessonMetal–Acid Hydrogen Calculations
Many suitable metals react with dilute nonoxidizing acids to release hydrogen. The mass of metal can therefore predict a gas amount, but only after the particular reaction is…
Explore lesson ChemistryLessonMetal–Semiconductor Contacts
A semiconductor device needs metal leads. A poorly chosen lead can form its own rectifying junction and dominate the measured response, even when the semiconductor interior is…
Explore lesson ChemistryLessonMetallic and Network Bonding Revisited
An elemental substance need not consist of isolated molecules. Copper, diamond and solid iodine illustrate three different ways to organise atoms. Their properties follow from…
Explore lesson ChemistryLessonMetallic and Nonmetallic Character
The left and center of the periodic table contain most metals, while nonmetals concentrate toward the upper right. This broad map helps anticipate bonding, conductivity and…
Explore lesson ChemistryLessonMetallic Bonding and Mobile Electrons — Bonding and Lewis Structures
A copper wire conducts electricity as a solid and can be drawn into long strands. A sodium chloride crystal usually does neither under comparable conditions. Both contain ordered…
Explore lesson ChemistryLessonMetallic Bonding and Mobile Electrons — Metals, Reactivity Series and Metallurgy Basics
Why can a metal wire conduct current while also bending without shattering? A basic metallic-bonding model represents metal atoms as positive ion cores in an ordered structure…
Explore lesson ChemistryLessonMetallic Bonding Compared with Ionic and Covalent
A copper wire conducts as a solid and can bend without breaking into a salt-like powder. Metallic bonding explains these properties using electrons spread through a structure of…
Explore lesson ChemistryLessonMetallic Character Across a Period — Periodic Classification and Trends
Period three begins with metallic sodium and magnesium and ends with non-metallic chlorine and argon, with intermediate behaviour between. Metallic character generally decreases…
Explore lesson ChemistryLessonMetallic Character Across a Period — The Periodic Table: Basics
Walk along any period of the periodic table, from left to right, and you pass from shiny, reactive metals to dull non-metals and finally to an unreactive noble gas. This gradual…
Explore lesson ChemistryLessonMetallic Character Down a Group — Periodic Classification and Trends
Down many groups, atoms grow larger and outer electrons become more shielded. That often makes electron loss easier and metallic behaviour more prominent. Group 16 shows the…
Explore lesson ChemistryLessonMetallic Character Down a Group — The Periodic Table: Basics
Elements in the same group share the same number of valence electrons, so they behave alike. Yet a group is not a set of identical twins. Look at Group 14: it starts with carbon…
Explore lesson ChemistryLessonMetalloids and Boundary Behaviour
Silicon appears near the staircase often drawn between metals and non-metals. It forms a covalent network and behaves as a semiconductor in suitable pure or doped forms, unlike a…
Explore lesson ChemistryLessonMetalloids: Elements on the Borderline — Metals and Non-metals
The periodic-table staircase is not a hard border. Silicon and germanium lie near it and are commonly called metalloids because their behaviour does not fit a simple…
Explore lesson ChemistryLessonMetalloids: Elements on the Borderline — The Periodic Table: Basics
Not every element fits neatly into the metal or non-metal box. Along the staircase line sit a handful of elements that look partly like metals yet behave partly like non-metals.…
Explore lesson ChemistryLessonMetallurgy Problem Set
Metallurgy problems often mix a qualitative question about reactivity with a quantitative question about ore mass or gas output. Solve the chemistry first: identify the mineral…
Explore lesson ChemistryLessonMetallurgy, Energy and the Environment
Metallurgy delivers useful materials but also moves huge amounts of matter and energy. Ore mining, concentration, reduction, electrolysis, refining and fabrication each have…
Explore lesson ChemistryLessonMetals and Metallurgy: Unit Review
Metals are useful because of their structures and properties, but they usually arrive in nature as minerals mixed with other material. This unit connects the reactivity series…
Explore lesson ChemistryCollectionMetals and Non-metals
Study Metals and Non-metals with 40 free lessons, worked examples, and answered practice questions.
Explore lesson ChemistryLessonMetals and Non-metals on the Periodic Table — Metals and Non-metals
The periodic table groups elements by atomic number and recurring properties. A zigzag or “staircase” line is often drawn across its right-hand side to help separate the broad…
Explore lesson ChemistryLessonMetals and Non-metals on the Periodic Table — The Periodic Table: Basics
The periodic table is not just a list of elements in order; it is a map. One of the first things a chemist reads from that map is whether an element is a metal or a non-metal. A…
Explore lesson ChemistryLessonMetals and Non-metals: Unit Review
This unit links what metals are like to what they do. Conductivity and malleability arise from metallic structure, while reaction patterns reflect electron transfer and the…
Explore lesson ChemistryLessonMetals as Chemical Materials
Metals appear in wiring, tools, vehicles and buildings because their chemistry supports useful physical properties. Most elemental metals conduct electricity, can be shaped and…
Explore lesson ChemistryLessonMetals Burning in Oxygen
Many metals react with oxygen to form oxides. Burning magnesium is a clear example of a reaction that is both combination and combustion. The oxide formula depends on the metal's…
Explore lesson ChemistryLessonMetals Displacing Metals from Solution
When a more reactive metal enters a suitable solution containing ions of a less reactive metal, the solid metal can replace the dissolved one. Iron in copper(II) sulfate is a…
Explore lesson ChemistryLessonMetals Form Positive Ions
Many metals form positive ions when they react with non-metals or acids. The positive charge does not mean protons were added. It means one or more electrons were removed from a…
Explore lesson ChemistryLessonMetals in Biology
Biology uses metal ions to bind gases, transfer electrons and activate water. Haemoglobin, cytochromes and zinc enzymes provide three distinct roles. The same Fe element appears…
Explore lesson ChemistryLessonMetals in Nature: Ores and Minerals
Metals rarely occur as pure elements in Earth's crust. Aluminium is commonly associated with oxygen-rich minerals, while lead often appears as sulfide. HSAB preferences help…
Explore lesson ChemistryLessonMetals Reacting with Cold Water
Highly reactive metals can react with cold water. Group 1 metals such as lithium, sodium and potassium make a metal hydroxide and hydrogen gas. Calcium, a Group 2 metal, can also…
Explore lesson ChemistryLessonMetals Reacting with Dilute Acids — Metals and Non-metals
Many metals above hydrogen in the reactivity series release H₂ when placed in a suitable dilute non-oxidising acid. The metal forms a cation, the acid's anion helps form a salt…
Explore lesson ChemistryLessonMetals Reacting with Dilute Acids — Metals, Reactivity Series and Metallurgy Basics
Some metals release hydrogen when placed in dilute hydrochloric or sulfuric acid. The metal loses electrons, and hydrogen ions gain them to form H₂. The reaction is useful for…
Explore lesson ChemistryLessonMetals Reacting with Dilute Acids — Types of Chemical Reactions
Many metals above hydrogen in the reactivity series react with suitable dilute acids to form a salt and hydrogen gas. The metal's ion charge fixes the salt formula, and…
Explore lesson ChemistryLessonMetals Reacting with Oxygen — Metals and Non-metals
Some metals burn rapidly in oxygen, while others slowly develop a surface layer. Both can involve oxidation, but the appearance and rate depend on the metal and conditions.…
Explore lesson ChemistryLessonMetals Reacting with Oxygen — Metals, Reactivity Series and Metallurgy Basics
Many metals combine with oxygen to form oxides, but their appearance and rate vary dramatically. Magnesium burns brightly when heated, aluminium forms a thin protective surface…
Explore lesson ChemistryLessonMetals Reacting with Steam
Some metals that do little with cold water can react with steam when heated. The common school pattern is metal + steam → metal oxide + hydrogen. Magnesium, zinc and iron…
Explore lesson ChemistryLessonMetals Reacting with Water
Some metals react with water and release hydrogen gas. Highly reactive metals may react with cold liquid water to form a hydroxide; less reactive metals may require hot steam and…
Explore lesson ChemistryLessonMetals Reacting with Water and Steam
“A metal reacts with water” is incomplete without temperature and metal identity. Sodium reacts strongly with cold water, magnesium reacts much more slowly with cold water but…
Explore lesson ChemistryLessonMetals That Do Not React with Dilute Acids
Copper, silver and gold appear below hydrogen in the common school reactivity series. They generally do not produce H₂ when exposed to dilute non-oxidising acids such as…
Explore lesson ChemistryLessonMetals, Non-metals and Metalloids
There are well over a hundred elements, and learning each one separately would be overwhelming. Chemists make the task easier by sorting elements into groups that behave in…
Explore lesson ChemistryLessonMetals, Non-metals and the Type of Bond
Before drawing electrons, identify the elements involved. Sodium with chlorine, carbon with oxygen, and copper with copper lead to different useful bonding descriptions. The…
Explore lesson ChemistryLessonMetals, Nonmetals and Metalloids
The periodic table broadly separates metals from nonmetals, with some elements near the boundary called metalloids. The labels summarize patterns in bonding, conductivity and…
Explore lesson ChemistryCollectionMetals, Reactivity Series and Metallurgy Basics
Study Metals, Reactivity Series and Metallurgy Basics with 60 free lessons, worked examples, and answered practice questions.
Explore lesson ChemistryLessonMetals, Semiconductors and Insulators
Copper conducts electricity readily, silicon can be controlled by tiny impurity concentrations, and diamond is normally an electrical insulator. Band theory connects these…
Explore lesson ChemistryLessonMetamerism and Tautomerism
Some isomer labels describe a very specific change in connectivity. “Metamerism” compares how carbon groups are distributed around a linking atom or group. “Tautomerism”…
Explore lesson ChemistryLessonMethane and Carbon's Four Bonds
Carbon's four valence electrons allow it to make four ordinary bonds in methane, CH₄. A Lewis diagram often places carbon in the center of a flat cross with four hydrogens. That…
Explore lesson ChemistryLessonMethanol Synthesis from Synthesis Gas
Methanol is a useful industrial product and feedstock for further synthesis. One established route reacts carbon oxides with hydrogen in a catalytic synthesis loop. The route…
Explore lesson ChemistryLessonMethod Validation and Quality Control
A method can work once and still fail tomorrow. Validation establishes that it is suitable for a defined analyte, matrix and concentration range. Routine quality control checks…
Explore lesson ChemistryLessonMicelles and Critical Micelle Concentration
Soap solutions behave differently once enough surfactant is present. At low concentration, many molecules occupy interfaces or remain separate in water. At higher concentration…
Explore lesson ChemistryLessonMicelles and Grease Removal
Soap can help water lift grease because its molecules can interact with both oil and water. In suitable aqueous conditions, soap molecules gather around oily material or assemble…
Explore lesson ChemistryLessonMichael Addition
An alpha,beta-unsaturated carbonyl compound contains an alkene next to C=O. That arrangement gives a carbon nucleophile two possible electrophilic sites: the carbonyl carbon and…
Explore lesson ChemistryLessonMichaelis-Menten Kinetics
An enzyme may work faster as substrate concentration rises, but the rate cannot increase indefinitely when the number of active sites is fixed. Michaelis–Menten kinetics…
Explore lesson ChemistryLessonMichaelis–Menten Kinetics
Enzymes are protein catalysts that can accelerate reactions by factors of a million or more. In 1913 Leonor Michaelis and Maud Menten showed that enzyme rates rise with substrate…
Explore lesson ChemistryLessonMicrokinetic Models
A mechanism becomes predictive when its elementary steps are combined with rate constants and balances for every relevant intermediate and site. A microkinetic model does this…
Explore lesson ChemistryLessonMicrostates and Boltzmann Entropy
Boltzmann's relation S = k_B ln Ω connects entropy with the number of microscopic arrangements compatible with a macroscopic state, when those microstates are equally probable.…
Explore lesson ChemistryLessonMicrostates, Configurations and Weight
Suppose a fixed amount of energy is shared among a group of molecules. There are many ways to do this: one molecule might hold all the energy, or it might be spread thinly across…
Explore lesson ChemistryLessonMigratory Insertion and Beta-Hydride Elimination
An organometallic catalyst can build a carbon chain by inserting an alkene into a metal–carbon bond. The resulting metal alkyl may then undergo beta-hydride elimination…
Explore lesson ChemistryLessonMillikan and the Charge of the Electron
Thomson's experiments supplied a ratio of charge to mass. To separate those quantities, scientists needed an independent measurement. Millikan's oil-drop work measured the tiny…
Explore lesson ChemistryLessonMiscible and Immiscible Liquids
Two clear liquids need not form one clear solution when poured together. Ethanol and water mix in all proportions at ordinary conditions, while oil and water usually separate…
Explore lesson ChemistryLessonMiscible Liquids and Boiling Points
Water and ethanol mix perfectly: pour one into the other and you get a single clear liquid with no layers. That makes a separating funnel useless. Their boiling points are…
Explore lesson ChemistryLessonMixed Basic-Concepts Problem Set
Longer chemistry problems mix familiar conversions. The difficult part is often deciding which relationship applies first: mass to moles, composition to formula, coefficient…
Explore lesson ChemistryLessonMixed Functional-Group Classification
After learning one functional group at a time, mixed structures test whether recognition is based on actual bonds. An oxygen atom may belong to an alcohol, ether, ketone, acid or…
Explore lesson ChemistryLessonMixed Gas and Reaction Stoichiometry Challenge
Many examination problems combine two ideas that students usually meet separately: reaction stoichiometry and the behaviour of gas mixtures. A vessel is filled with several…
Explore lesson ChemistryLessonMixed Group and Bonding Problems
The periodic table helps predict MgCl₂ and the polarity of H–Cl, but the methods differ. Ionic formula questions balance whole charges; covalent-bond questions compare attraction…
Explore lesson ChemistryLessonMixed Kinetic and Transport Control
Most electrode currents are not controlled by only one process at every potential. Near equilibrium, charge-transfer kinetics may dominate. As overpotential increases, reactant…
Explore lesson ChemistryLessonMixed Lewis and Formal-Charge Problems
Mixed Lewis questions are harder than isolated one-skill exercises because several checks must be applied in the right order. A drawing may have the right formula but too many…
Explore lesson ChemistryLessonMixed Lewis-to-Shape Workflow
Many examination questions ask for a shape or polarity without displaying a structure. The reliable path starts at the formula and charge, then goes through electron budget…
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