Chemistry & Materials
Atoms, reactions, water, surfactants, materials, food chemistry and recycling.
Atoms, molecules and chemical bonds
Matter is built from atoms, and chemical bonds hold atoms together in molecules and extended structures.
GuideHow the periodic table organizes elements
The periodic table arranges elements by atomic number so repeating chemical patterns line up in groups.
GuideWhat happens in a chemical reaction
Chemical reactions rearrange atoms by breaking and forming bonds while conserving the number of each kind of atom.
GuideAcids, bases and pH
Acid-base chemistry describes proton transfer and related changes in aqueous solutions.
GuideWhy water has unusual properties
Water's molecular shape and hydrogen bonding help explain its high heat capacity, surface tension and unusual behaviour when freezing.
GuideWhy water expands when it freezes
Most materials contract as they cool, but ordinary ice forms a crystal structure that is less dense than liquid water.
GuideSurface tension, droplets and soap bubbles
Surface tension comes from cohesive molecular forces at a liquid surface.
GuideHow soap and detergents work
Surfactants have molecular regions that interact differently with water and oily substances, helping detach and disperse soils.
GuideHow adhesives stick
Adhesives work through a combination of surface wetting, molecular attraction, mechanical interlocking and internal strength.
GuideWhy glass is transparent—and why it can break
Ordinary glass is an amorphous solid whose electronic structure allows much visible light to pass through while its brittle structure limits how it handles cracks.
GuidePolymers and plastics
Polymers are long-chain molecules whose composition and structure create a wide range of flexible, rigid, clear, tough or heat-resistant materials.
GuideThe science of textile fibres
Fabric behaviour comes from fibre chemistry, yarn structure, weave or knit construction and finishing treatments.
GuideFragrance, volatile molecules and smell
Smell begins when volatile molecules reach olfactory receptors in the nose and trigger patterns of neural signals.
GuideThe science of fermentation
Fermentation uses microbial metabolism to transform sugars and other compounds into products such as acids, gases or alcohols.
GuideHow heat transforms food
Cooking changes food through heat transfer, water movement, protein changes, starch behaviour and chemical reactions.
GuideWhat the Maillard reaction is
The Maillard reaction is a family of heat-driven reactions involving amino compounds and reducing sugars that produce many browned-food aromas, flavours and pigments.
GuideWhy oil and water can form emulsions
An emulsion disperses droplets of one liquid inside another liquid that would normally separate.
GuideHow leavening makes baked foods rise
Leavening creates gas bubbles that expand within a dough or batter while structure develops around them.
GuideWhat recycling can and cannot do to materials
Recycling collects and reprocesses materials, but the science and economics depend on contamination, separation, material degradation and available markets.
GuideBiodegradable and compostable materials are not the same thing
Environmental labels describe different processes and conditions, and a material that breaks down in an industrial composting facility may not do so in soil, water or a home compost pile.