Science Concepts Encyclopedia

Explore key science concepts like density, acid-base reactions, and crystal growth. Each concept page explains the science, shows a visual diagram, and connects to hands-on experiments you can try.

Acids & Bases

How acids and bases interact, from the color-changing indicators that reveal pH to the fizzing neutralization reactions you can see and measure in everyday experiments.

Acid Erosion

Acid erosion is what happens when an acid slowly eats away at a solid material, like vinegar dissolving an eggshell.

Acid-Base Reactions

Acid-Base Reactions is what happens when an acid and a base mix and create new things like bubbles or color changes.

Anthocyanins

Anthocyanins is the natural color in red cabbage that changes from pink to green depending on whether a liquid is acidic or basic.

Calcium Carbonate Reactions

Calcium Carbonate Reactions is what happens when an acid like vinegar meets a calcium carbonate surface like an eggshell, dissolving it and producing bubbles.

Carbon Dioxide Gas Production

Carbon Dioxide Gas Production is what happens when two substances mix and release carbon dioxide gas, like the fizzing you see when baking soda meets vinegar.

Chemical Indicators

Chemical Indicators are substances that change color to show whether a chemical reaction has happened or how acidic a liquid is.

Neutralization

Neutralization is what happens when an acid and a base cancel each other out, creating something milder.

pH Indicators

pH Indicators is a group of substances that change color to show whether a liquid is an acid or a base.

Fluids, Density & Gases

Why some things float and others sink, how gases push and compress, and what happens when liquids refuse to mix. These concepts connect through the shared physics of pressure, mass, and volume.

Buoyancy

Buoyancy is the upward push water gives to anything placed in it.

Combustion

Combustion is a chemical reaction where a substance burns by combining with oxygen, releasing heat and light.

Density

Density is how much stuff is packed into a space, which is why some things float and others sink.

Gas Pressure

Gas Pressure is the push that trapped gas makes against the walls of its container, like the force that launches a film canister rocket.

Immiscible Liquids

Immiscible Liquids is what happens when two liquids, like oil and water, refuse to mix and instead form separate layers.

Osmosis and Dehydration

Osmosis and dehydration is how water moves through a thin barrier, pulling moisture out of things like an orange soaked in alcohol.

Electricity & Electrochemistry

From batteries to electrolysis, these concepts explore how chemical reactions produce electricity and how electricity drives chemical change. Metal reactivity ties them all together.

Displacement Reactions

Displacement Reactions is when a stronger metal pushes a weaker metal out of a solution, trading places with it.

Electrochemical Cells

Electrochemical Cells is how two different metals in a liquid create electricity, like a homemade battery built from zinc and copper.

Electrolysis

Electrolysis is using electricity to break water apart into hydrogen gas and oxygen gas.

Hydrogen Gas

Hydrogen gas is the lightest gas in the world, and you can make it by running electricity through water.

Metal Reactivity Series

Metal Reactivity Series is a ranking of metals by how eagerly each one reacts, showing why a zinc-and-copper battery produces more voltage than other metal pairs.

Voltage and Electric Current

Voltage and electric current is the push and flow of tiny charges through a wire.

Heat & Energy

How temperature drives reactions faster, makes matter change state, and moves heat through fluids. These concepts share a common thread: energy in motion.

Convection

Convection is the way heat moves through a liquid or gas by making warmer parts rise and cooler parts sink.

Exothermic Reactions

Exothermic Reactions is when a chemical change gives off heat, like the warm foam that bursts from an elephant toothpaste experiment.

Phase Changes

Phase Changes is what happens when matter shifts between solid, liquid, and gas, like ice melting into water.

Sublimation

Sublimation is when a solid turns directly into a gas without melting into a liquid first.

Temperature Effects on Reaction Rate

Temperature Effects on Reaction Rate is how heating or cooling a substance changes how fast it reacts, like sugar dissolving faster in hot water than cold.

Crystals & Solutions

What happens when you dissolve, concentrate, and crystallize. From growing crystals to understanding why salt melts ice, these concepts explore the boundary between dissolved and solid.

Colligative Properties

Colligative Properties are ways that adding a substance to a liquid changes how it freezes, boils, or behaves, based on how many particles you add.

Crystal Growth

Crystal growth is what happens when tiny particles in a liquid slowly stack together into a solid shape.

Dissolution and Solubility

Dissolution and solubility is how well something breaks apart and mixes into a liquid until it disappears.

Evaporation

Evaporation is when a liquid turns into a gas and moves into the air, even without boiling.

Freezing Point Depression

Freezing Point Depression is what happens when adding something like salt or sugar to water makes it freeze at a colder temperature.

Supersaturation

Supersaturation is when water holds more dissolved material than it normally can, so crystals form as it cools.

Light & Color

How light interacts with matter — from glow-in-the-dark phosphorescence to the UV absorption that sunscreen blocks. Chromatography reveals hidden colors; Beer's Law measures concentration through light.

Beer's Law

Beer's Law is the rule that light gets weaker as it passes through more of a colored liquid, like sunscreen blocking UV rays.

Chemiluminescence

Chemiluminescence is light produced by a chemical reaction instead of heat, like the glow inside a glow stick.

Chromatography

Chromatography is a way to separate the hidden colors inside a mixture by letting a liquid carry them apart on paper.

Phosphorescence

Phosphorescence is the glow some materials give off in the dark after soaking up light.

UV Absorption

UV Absorption is what happens when a material soaks up ultraviolet light instead of letting it pass through.

Surface & Interface

The science at the boundary: surface tension holds water drops together, surfactants break that tension, and capillary action pulls liquids through narrow spaces.

Capillary Action

Capillary action is the way water travels upward through narrow spaces on its own, like when a paper towel soaks up a spill.

Surface Tension

Surface Tension is the thin, stretchy skin that forms on top of water because water pulls itself together.

Surfactants

Surfactants are molecules in soap that grab onto both water and oil, letting you wash greasy things clean.

Materials & Reactions

How materials transform through chemical reactions — rust eats iron, soap forms from fat, eggs cook irreversibly, and catalysts speed it all up without being consumed.

Atomic Structure

Atomic structure is the arrangement of tiny particles inside an atom, which you can model by grouping dried beans into a center cluster and an outer ring.

Catalysis

Catalysis is when a substance speeds up a chemical reaction without being used up itself, like yeast making hydrogen peroxide foam instantly.

Corrosion

Corrosion is the slow chemical breakdown of metal when it reacts with water, air, or other substances around it.

Oxidation

Oxidation is a chemical reaction where a substance combines with oxygen, like when lemon juice on paper turns brown from heat.

Protein Denaturation

Protein Denaturation is what happens when heat or acid makes proteins in milk unfold and clump together into solid chunks.

Saponification

Saponification is the chemical reaction that turns fat or oil into soap when mixed with a strong base.