Matter
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The Simple English Wiktionary has a definition for: matter. |
Matter is the substance of which all material things are made. Matter can be directly experienced through the senses.
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Properties of matter [change]
Matter exhibits various quantitative, measurable properties such as mass, weight, volume, density, color, as well as qualitative properties such as taste and smell, for instance.
Examples of matter [change]
All physical objects in the universe are made of matter: galaxies, stars and planets, rocks, water and air. Living organisms like plants, animals and humans are also composed of matter.
These objects can contain energy, which is not made of matter but allows them to interact with each other by exchanging kinetic energy, heat, light, sound waves, etc.
Humans, and probably other animals, can also experience emotions or have ideas, which are made neither of matter nor of energy, as defined in physics.
Composition [change]
Scientists have long sought to understand the structure and composition of matter by cutting or breaking matter into smaller and smaller pieces. Hence, living organisms are made up of cells, which are composed of molecules, which are sets of atoms bounded together. Each atom, in turn, is an assemblage of elementary particles.
States of matter [change]
Physicists also classify matter in a few broad categories, called states with quite different properties:
- Solids are material objects made up of molecules and atoms so strongly bonded together that they tend to keep their shape even when moved around, though they can deform under stress. Examples: a rock, a table, a knife, a block of ice.
- Fluids are amounts of matter composed of molecules and atoms weakly bonded together. They do not have a proper shape. There are two types of fluids:
- Liquids include condensed forms of matter, like solids, but where the bonds between the constituting elements (molecules, atoms) allow them to move with respect to each other while continuing to stick together in bulk: they maintain a definite surface. Liquids adopt the shape of the recipients in which they are contained. Examples: water, oil, blood, lava, soft drinks.
- Gases are amounts of matter where the bonds between the constituting elements (molecules, atoms) are so loose or weak that they can move independently from each other. Gases do not exhibit a proper surface, they tend to expand to occupy the whole volume available. Examples: air, water vapor, helium.
- Plasmas are made of ionized matter, they are mostly of interest to scientists. Examples: the Earth's ionosphere, the Sun's corona.
A given amount of matter may change from one state to another depending on its temperature and pressure. On Earth, water can exist simultaneously in three states: solid (ice), liquid water (lakes, oceans) and gas (vapor or steam).
