pH
Skincare
Why does pH matter?
Healthy skin is mildly acidic. Product chemists adjust formulas so cleansers and moisturizers work effectively without disrupting that balance.
Hidden chemistry,
ordinary moments.
Chemical engineers use chemistry, physics, math, and design to turn scientific ideas into useful products and large-scale processes.
H₂O
Clean water
How is water purified?
Treatment systems combine filtration with chemical processes such as coagulation and disinfection to remove particles and harmful microorganisms.
CO₂
Food
What makes bread rise?
Yeast converts sugars into carbon dioxide gas. That gas becomes trapped in dough, forming bubbles that expand during baking.
02 — Foundations
Matter, atoms, and bonds.
Matter is anything that has mass and takes up space. Every sample of matter is built from atoms—the tiny units that retain the identity of an element. Their arrangement and motion explain the properties we observe.
Inside an atomProtons carry a positive charge,
neutrons have no charge, and electrons carry a negative charge.
Protons and neutrons form the nucleus while electrons occupy regions
around it.
Elements and compoundsAn element contains one type
of atom. A compound forms when atoms of different elements join in a
fixed ratio, like H₂O.
Ionic bondingElectrons transfer from one atom to
another, creating oppositely charged ions that attract. Table salt,
NaCl, is a familiar example.
Covalent bondingAtoms share electrons. Water,
carbon dioxide, sugars, and molecules in living things depend
heavily on covalent bonds.
One science, many specialties.
Organic chemistry
Studies carbon-based compounds, including fuels, medicines, plastics, and molecules found in living organisms.
Inorganic chemistry
Explores metals, minerals, salts, ceramics, catalysts, and many compounds not based mainly on carbon.
Physical chemistry
Uses physics and math to explain energy, reaction rates, molecular motion, and why chemical changes occur.
Analytical chemistry
Identifies what substances contain and how much is present using measurements, separations, and instruments.
Biochemistry
Examines chemical processes in living things, from proteins and DNA to metabolism and cellular energy.
Environmental chemistry
Studies chemical behavior in air, water, and soil and helps scientists understand pollution and design solutions.
04 — Reactions
Atoms rearrange.
Atoms rearrange.
Matter changes.
A chemical reaction breaks and forms bonds, turning reactants into products. The atoms themselves are conserved, which is why chemical equations must be balanced.
2H₂
hydrogen+O₂
oxygen→2H₂O
water
hydrogen+O₂
oxygen→2H₂O
water
Exothermic reactionsRelease energy to the
surroundings, often as heat or light. Combustion is one example.
Endothermic reactionsAbsorb energy from the
surroundings. Photosynthesis requires energy from sunlight.
Reaction rateTemperature, concentration, surface
area, and catalysts affect how often particles collide successfully.
Acids and basesAcids donate hydrogen ions and bases
accept them. The pH scale describes how acidic or basic a
water-based solution is.
Meet six essential elements.
The periodic table organizes elements by atomic number and repeating chemical behavior. Select an element to learn where it appears.
Hydrogen: Atomic number 1. Hydrogen is the lightest
element and is found in water, fuels, acids, and nearly every organic
molecule.
06 — Chemical engineering
From a reaction to the real world.
Chemists often study what substances are and how they react. Chemical engineers combine that knowledge with physics, mathematics, economics, and design to produce useful materials safely and efficiently at a larger scale.
Discover
Study a useful molecule, material, or reaction in the laboratory.
Design
Create a process with reactors, separation equipment, heat transfer, and controls.
Scale
Move from a small experiment to reliable production while managing cost and resources.
Improve
Make the process safer, cleaner, faster, and less wasteful.
Energy
Batteries, hydrogen, biofuels, carbon capture, and cleaner manufacturing.
Health
Medicines, medical materials, sterile production, and drug-delivery systems.
Sustainability
Water treatment, recyclable materials, pollution prevention, and efficient resource use.
Chemistry words to know.
AtomThe smallest unit of an element that retains
its chemical identity.
MoleculeTwo or more atoms chemically bonded
together.
IonAn atom or molecule with a net electrical
charge.
CatalystA substance that increases reaction rate
without being consumed overall.
SolutionA uniform mixture in which a solute is
dissolved in a solvent.
MoleA counting unit equal to about 6.022 × 10²³
particles.
Particles in motion.
Solid
Particles stay close and mainly vibrate in fixed positions. Solids have a definite shape and volume. Crystalline solids have repeating structures; amorphous solids, such as glass, do not have long-range order.
Liquid
Particles remain close but move past one another. Liquids have a definite volume but take the shape of their container. Intermolecular forces influence viscosity, surface tension, and boiling point.
Gas
Particles are far apart and move rapidly. Gases expand to fill their container and are compressible. Pressure comes from particle collisions with the container walls.
Plasma
At very high energy, electrons separate from atoms and form an ionized gas. Stars, lightning, and some specialized lamps contain plasma.
Phase changes: melting, freezing, vaporization,
condensation, sublimation, and deposition are physical changes. The
substance’s identity stays the same while particle energy and
arrangement change.
Patterns that predict behavior.
Periods run horizontally and groups run vertically. Elements in the same group often behave similarly because they have similar valence-electron patterns.
| Trend | Across a period → | Down a group ↓ | Meaning |
|---|---|---|---|
| Atomic radius | Generally decreases | Generally increases | Approximate atom size |
| Ionization energy | Generally increases | Generally decreases | Energy needed to remove an electron |
| Electronegativity | Generally increases | Generally decreases | Attraction for shared electrons |
| Metallic character | Generally decreases | Generally increases | Tendency to show metallic properties |
Chemistry’s counting system.
Atoms are too small to count individually, so chemists use the mole. One mole contains approximately 6.022 × 10²³ particles, called Avogadro’s constant.
Molar mass
The mass of one mole of a substance, measured in grams per mole, comes from adding the atomic masses in its formula.
moles = mass ÷ molar massMole ratios
Coefficients in a balanced equation give reacting ratios. In 2H₂ + O₂ → 2H₂O, two moles of hydrogen react with one mole of oxygen.
Limiting reactant
The reactant used up first limits how much product can form. Other reactants may remain in excess.
Percent yield
Actual experiments may produce less than the theoretical maximum because of incomplete reactions, side reactions, or product loss.
% yield = actual ÷ theoretical × 100Mixtures, pressure, and particles.
Solute + solvent
A solution is a homogeneous mixture. The solute is dissolved, while the solvent does the dissolving. Water is a common polar solvent, but it cannot dissolve every substance.
Concentration
Molarity reports moles of solute per liter of solution. Dilution lowers concentration by adding solvent.
M = mol ÷ LGas relationships
Pressure, volume, temperature, and amount are connected. Heating a flexible gas sample usually increases volume; compressing it increases pressure.
PV = nRTWhere chemical energy goes.
System and surroundings
The system is the part being studied; everything else is the surroundings. Energy moves between them as heat or work.
Enthalpy
The enthalpy change, ΔH, tracks heat transferred at constant pressure. Negative ΔH indicates an exothermic process; positive ΔH indicates an endothermic one.
Bond energy
Breaking bonds requires energy, while forming bonds releases energy. The balance helps determine whether a reaction absorbs or releases heat.
Specific heat
Substances require different amounts of energy to change temperature. Water’s high specific heat helps moderate temperatures.
q = mcΔTHow fast—and how far?
Collision theory
Particles must collide with enough energy and the correct orientation to react. Higher temperature usually increases collision frequency and energy.
Activation energy
Reactions must overcome an energy barrier. Catalysts provide an alternate pathway with lower activation energy.
Dynamic equilibrium
At equilibrium, forward and reverse reaction rates are equal. Concentrations remain constant, but both reactions continue microscopically.
Le Châtelier’s principle
When an equilibrium system is disturbed, it shifts in the direction that partially opposes the change.
Electrons create electricity.
Oxidation-reduction reactions transfer electrons. Oxidation is loss of electrons; reduction is gain. The two always occur together.
Voltaic cellsA spontaneous redox reaction produces
electrical energy. Electrons travel through an external circuit from
anode to cathode.
Electrolytic cellsExternal electrical energy drives
a nonspontaneous reaction, useful in electroplating and industrial
production.
BatteriesCarefully selected electrochemical
reactions create voltage. Rechargeable batteries reverse parts of
the chemistry while charging.
CorrosionEnvironmental redox reactions oxidize
metals. Coatings, sacrificial metals, and material selection help
control corrosion.
Changes inside the nucleus.
Chemical reactions rearrange electrons and bonds, while nuclear processes change atomic nuclei. Isotopes are atoms of the same element with different numbers of neutrons.
Radioactive decay
Some unstable nuclei naturally transform and release radiation. Half-life is the time required for half of a radioactive sample’s nuclei to decay.
Fission and fusion
Fission splits heavy nuclei, while fusion joins light nuclei. Both convert a small amount of mass into energy under very different conditions.
Good science needs good data.
Core laboratory habits
- Follow instructor directions and read labels first.
- Wear required eye protection and protective clothing.
- Never taste chemicals or directly inhale fumes.
- Use a fume hood when instructed.
- Report spills, broken glass, and injuries immediately.
- Dispose of chemicals only as directed.
- Keep food and drinks outside the laboratory.
- Wash hands after laboratory work.
Accuracy vs. precision: accuracy is closeness to an
accepted value; precision is how closely repeated measurements agree.
Significant figures communicate measurement precision.
The systems behind modern life.
Reactors and reaction engineering
Engineers select reactor types, temperatures, pressures, catalysts, and residence times for safe and useful conversion.
Separations
Distillation, filtration, absorption, extraction, crystallization, and membranes separate products from mixtures. Separation can be one of a process’s largest energy costs.
Heat and mass transfer
Engineers predict how thermal energy and chemical species move through equipment so processes remain efficient and controlled.
Process control
Sensors measure temperature, flow, level, and pressure. Control systems adjust equipment to keep operation stable.
Process safety
Engineers identify hazards, design layers of protection, and plan for abnormal conditions to reduce risk.
Sustainable design
Modern processes aim to use less energy and water, reduce waste, choose safer materials, and consider a product’s full life cycle.
Six more ways chemistry shapes our world.
These fields overlap constantly. A sunscreen, battery, medicine, or recyclable package can involve several of them at once.
Bonding beyond the basics
Electron pairs repel one another, so they arrange themselves to reduce repulsion. This helps explain why carbon dioxide is linear while water is bent. Shape and polarity influence boiling point, solubility, and biological activity.
shape → polarity → propertiesAcids, bases, and buffers
Brønsted–Lowry acids donate protons and bases accept them. Strong describes how completely a substance ionizes; concentrated describes how much is present. Buffers resist sudden pH changes using a weak acid–base pair.
pH = −log[H⁺]Organic molecules
Carbon forms stable chains, rings, and four covalent bonds. Functional groups—such as hydroxyl, carboxyl, and amino groups—give molecules recognizable reaction patterns and properties.
Polymers
Polymers are long molecules made from repeating monomers. Their chain length, branching, cross-linking, and intermolecular forces can produce materials ranging from flexible rubber to strong fibers.
Biochemistry
Proteins act as structures, signals, and enzymes; carbohydrates store energy and provide structure; lipids form membranes; and nucleic acids store genetic information. Molecular shape helps each perform its role.
Green chemistry
Green chemistry aims to prevent waste, use safer substances, improve energy efficiency, and design products that work without creating unnecessary harm across their life cycle.
Don’t just read it. Try it.
Use these mini tools to practice calculations, vocabulary, and balanced equations.
Molar-mass explorer
Select a common compound to see how its atomic masses add up.
Choose a compound and press Calculate.
Chemistry flashcards
Click the card to reveal the answer, then move to the next one.
What is electronegativity?
Balance a reaction
Enter the smallest whole-number coefficients.
H₂ +
O₂ →
H₂O
Hint: count hydrogen and oxygen atoms on both sides.
Learning chemistry by building.
Chemistry, Everywhere is an ongoing student-created project that combines scientific research, clear communication, design, and technology.
Start with everyday observations: Why does bread rise? How is water cleaned? Why does pH matter?
Compare reliable chemistry references, define unfamiliar terms, and connect each concept to real applications.
Translate complex ideas into accurate, readable explanations without removing the important science.
Turn the learning into an interactive website, test the tools, and keep expanding it as knowledge grows.
What I’m learning
This project strengthens chemistry knowledge while building skills in research, scientific writing, web design, problem-solving, and communicating technical ideas.
What comes next
Future updates can explore more elements, real chemical-engineering case studies, original diagrams, and short explanations connected to current class topics.
Trusted places to keep learning
This student guide is educational and continues to grow. For technical definitions and reference data, explore the IUPAC Gold Book, American Chemical Society education resources, and NIST Chemistry WebBook.
21 — Knowledge check
Test your chemistry instincts.
Twelve quick questions. Your score appears when you finish.
22 — About me
Hi, I’m Maya.
A student, creator, and future chemical engineer.
I’m a high school student with a strong interest in chemistry, technology, and solving difficult problems. Chemistry fascinates me because tiny interactions between atoms can create huge changes in medicine, energy, materials, food, water, and everyday products.
I hope to study chemical engineering in college. I’m especially interested in how chemical engineers take discoveries from a laboratory and turn them into safe, efficient processes that can help people on a larger scale.
I also enjoy building technology projects and finding creative ways to explain complicated ideas. I made this website to explore chemistry beyond the classroom, share what I learn, and connect my interests in science and technology.
My interests: Chemistry · Chemical engineering · Technology · Scientific problem-solving · Creating useful projects
Created by Maya, a high school chemistry student.