Matter
Matter means objects which have mass even when not moving, which is a form of energy that matter has even when it is not moving.
Ordina matter is made of tiny particles called atoms. The atoms have spaces between them and they move or vibrate all the time. The particles move faster and move further apart when heated, and then reverse when cooled.
Baryonic matter
Nearly all matter that may be experienced in everyday life is baryonic matter. This includes atoms of any sort, and gives those the property of mass. Non-baryonic matter, as implied by the name, is any sort of matter that is not composed mainly of baryons. This might include neutrinos and free electrons, dark matter, such as supersymmetric particles, axions, and black holes.
The very existence of baryons is a significant issue in cosmology. It is assumed that the Big Bang produced a state with equal amounts of baryons and antibaryons. How baryons came to outnumber their antiparticles is called baryogenesis.
Properties of matter
Matter can be directly experienced through the senses. It has properties which can be measured, such as mass, volume, density, and qualitative properties such as taste, smell and colour, for instance.
Examples of matter
All physical bodies 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.
In physics, the universe also contains things that aren’t matter, including some elementary particles that have no rest mass. Photons (electromagnetic radiation such as light) are a familiar example.
In addition to its rest mass, matter can contain other forms of energy, which aren’t matter but allow them to interact with each other by exchanging kinetic energy, heat, light, sound waves, etc.
Outside of the physical sciences, there can be many other things that aren’t matter or energy. Just for example, emotions can be experienced or ideas can be had.
Composition
The structure and composition of matter is investigated by breaking matter into smaller and smaller pieces. Hence, living organisms are made up of cells. Cells are composed of molecules, which are sets of atoms bonded together. Each atom, in turn, is an assemblage of elementary particles.
States of matter
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. The particles in a plasma are a mixture between a liquid and a gas. The particles are free to move, like a liquid, and the attraction is weak, like a gas. This state of matter is not fully understood. An example of plasma can be found in lightning.
- A Bose–Einstein condensate (BEC) is a state of matter of a dilute gas of bosons cooled to temperatures very near absolute zero (0 K or −273.15 °C)
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).
Written for younger readers
Matter, in simpler words
This version comes from Wikijunior, a set of books written for children aged 8 to 11. It is shorter and uses plainer language than the article above.
From Wikijunior: Particles
As we have found out from the introduction, anything that occupies space and has mass is matter. However, not all matter is the same. Matter, in fact, can appear as three forms: liquid, solid and gas. Water is the only kind of matter whose all three states appear in nature. Therefore, we will use water as a primary example as we go through the three states of matter. Later in the book, we will also explain the three states of matter with the particle model.
The properties of matter are as follows:
- Solids’ shapes cannot be altered, and nor can its volume
- Liquids’ shapes can be altered, but not its volume
- Gases’ shapes can be altered (so it’s compressible), and so can its volume
These properties can be verified with a series of experiments. First, you can try to alter the shape of volume of solids. Try doing that to your pencil – it won’t budge. Then try to pour some water from a bottle to a cup. The shape changes. Now, if the bottle is full, but its size reduces, will the liquid spill? The answer is yes. Therefore, liquids have a fixed volume. Finally, try gases. If you transfer some coloured gas from one container to another, whose shapes and sizes are different, there will be no problem.
Sometimes matter can change from one state to another. For example, if you blow onto the surface of glass, the water vapour that comes out of your mouth transforms into liquid. If you put the piece of glass into a freezer, a few hours later it will become ice.
There are specific names for the changes of states.
Melting, freezing and boiling happen at fixed temperatures. The temperature of distinction between different states are called the melting point, the freezing point and the boiling point. For water, these points are 0°C, 0°C and 100°C respectively. Actually, the freezing and melting points of any matter are the same.
Condensation does not take place at a fixed temperature. There is a related process called evaporation, which does not take place at a fixed temperature, although a higher temperature does accelerate the rate of evaporation. Evaporation is the process in which a solid changes into a liquid. When your wound is sterillised, it feels cold as the alcohol evaporates, carrying with it heat.
- X is heated, so that transforms into another state. The initial form is not liquid. What is the current form? What is the process it went through?
- True or false? As the boiling point of Y is 300°C, it cannot change into its gaseous form at 250°C, nor change into liquid form at 350°C.
Answers:
- Liquid; melting
- False. Condensation and evaporation can happen at any temperature.
Where this page comes from
The article above is adapted from “Matter” on Simple English Wikipedia, by its contributors. We removed reference markers, navigation boxes and tables, expanded measurement templates into readable numbers, and kept the prose otherwise intact. The simpler version is adapted from Wikijunior on Wikibooks.
Both sources are published under CC BY-SA 4.0, so this page is published under the same licence. You may share and adapt it, including commercially, as long as you credit the original and keep the same licence.
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