Knowledge you can walk. Read the idea below, then step up to the general, across to peers or down to the specific.
Physical
Materials
Materials are the substances, or mixtures of substances, that objects are made of.
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The idea
A material is any substance, or mixture of substances, that makes up an object. The wood in a pencil, the steel in a bridge and the cotton in a shirt are all materials. Materials can be pure or impure, and they can come from living or non-living matter. Cotton and leather come from living things, while metals and stone come from the ground.
Scientists sort materials in several ways. They group them by physical and chemical properties, such as hardness, how well they carry heat, or whether they rust. They can also group them by where they formed in the earth or by the job they did in a living thing. Familiar groups include metals, plastics and other polymers, ceramics and glass, and natural fibers.
Materials science is the study of materials, their properties and their uses. Raw materials can be changed by purifying them, shaping them or mixing in other materials. Chemists can also make brand-new materials from raw ones through a process called synthesis. In industry, materials are the inputs that factories turn into products, and the kind and amount used help set what a product costs.
Check yourself
Question 1 of 2
What is it called when chemists make brand-new materials from raw ones?
Composition
what it's made of
- Substances — Each material is one substance or a mixture of several.
- Physical Properties — Traits such as hardness, density and how easily heat or electricity passes through.
- Chemical Properties — How a material reacts with other substances, for example whether it rusts or burns.
- Origin — Where a material comes from: living things, rocks and minerals, or a chemical process.
- Processing — Purifying, shaping or mixing raw materials changes how they behave.
Connection
how it relates
Under Physical
Change
how and why it evolves
- Past
- Early people shaped stone, wood, bone and clay, and later learned to work metals such as copper, bronze and iron.
- Now
- Today engineers pick the right material for each job, balancing strength, weight and price.
- Next
- Researchers will likely keep developing materials that are lighter, stronger and easier to recycle.