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Science: An Elementary Teacher’s Guide/States of Matter

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States of MatterEdit

In physics, a state of matter is one of the distinct forms that matter takes on. Four states of matter are observable in everyday life: solid, liquid, gas, and plasma. Many other states are known to exist only in extreme situations, such as Bose–Einstein condensates, neutron-degenerate matter and quark-gluon plasma, which occur in situations of extreme cold, extreme density and extremely high-energy color-charged matter respectively. Some other states are believed to be possible but remain theoretical for now. Matter is anything that has mass and takes up space. Atoms, molecules and ions is the matter that makes up all physical substances. Matter is anything that has mass and takes up space. If you are new to the idea of mass, it is the amount of stuff in an object. Matter exists in states: the classical solid, liquid, and gas; as well as the plasma.

The elements in the periodic table appear, at standard situations (P and T) as solid, liquid, or gas (rare elements which have uncertain state are marked with yellow)

Properties of Matter

Physical Properties

Each substance has physical properties that are different from other substances which include the following:

  • Size
  • Shape
  • Color
  • Odor
  • Appearance
  • Texture

Physical properties can be observed or measured without compromising the matter.

Chemical Properties

Chemical properties of matter can be described as "potential" to undergo a chemical change or reaction. For example:

  • Iron gets rust(iron oxide) when exposed to water. Iron gets run when reacts with oxygen in presence of water or air moisture.

A substance that reacts with another substances is consider active. While the substance that does not react with another substance is inert.


Solids can be considered to be hard as a rock or soft as fur. The key to a solid is that it holds its shape and won't flow like a liquid. A rock will always look like a rock unless something happens to it. The same goes for a diamond. A solid can hold it's shape because they have particles (ions, atoms or molecules) that are closely packed together. In a solid, particles are packed tightly together so they are unable to move about very much. Particles of a solid have very low kinetic energy. The electrons of each atom are in motion, so the atoms have a small vibration, but they are fixed in their position. Solids have a definite shape. They do not conform to the shape of the container in which they are placed. Solids can only change their shape by force, as when broken or cut. They also have a definite volume. The particles of a solid are already so tightly packed together that increasing pressure will not compress the solid to a smaller volume. Solids can be transformed into liquids by melting, and liquids can be transformed into solids by freezing. Solids can also change directly into gases through the process of sublimation, and gases can likewise change directly into solids through deposition.

Example: A cubed ice would be considered a solid


Liquids are a state found between a solid and a gas. An example of a liquid at room temperature are water, blood, and even lemonade.

A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure.

If you have different types of molecules dissolved in a liquid, it is called a solution. Lemonade is a solution of water, sugar, and lemon, a combination of molecules. In the liquid phase, the particles of a substance have more kinetic energy than those in a solid. The liquid particles are not held in a regular arrangement, but are still very close to each other so liquids have a definite volume. Liquids, like solids, cannot be compressed. The volume is definite if the temperature and pressure are constant. When a solid is heated above its melting point, it becomes liquid, given that the pressure is higher than the triple point of the substance. Particles of a liquid have just enough room to flow around each other, so liquids have an indefinite shape. A liquid will change shape to conform to its container. Force is spread evenly throughout the liquid, so when an object is placed in a liquid, the liquid particles are displaced by the object.

Example: taking the cubed ice and letting it melt into water would be considered a liquid


Gases are everywhere. A gas can be considered as a compressible fluid. Solid molecules are tightly compacted together, and liquid molecules are little spread out. Gas molecules are very spread out and are full of energy floating around randomly. Gas molecules can fill up any container with no consideration to size or shape. Gas particles have a great deal of space between them (much greater than the molecular size) and have high kinetic energy. The effect of intermolecular forces is small (or zero for an ideal gas). If unconfined, the particles of a gas will spread out indefinitely; if confined, the gas will expand to fill its container. When a gas is put under pressure by reducing the volume of the container, the space between particles is reduced, and the pressure exerted by their collisions increases. If the volume of the container is held constant, but the temperature of the gas increases, then the pressure will also increase. Gas particles have enough kinetic energy to overcome intermolecular forces that hold solids and liquids together, thus a gas has no definite volume and no definite shape. A liquid may be converted to a gas by heating at constant pressure to the boiling point, or else by reducing the pressure at constant temperature.

Example: From the ice cube forming it into a liquid then waiting for it to evaporate would be considered gas


A plasma is a hot ionized gas consisting of approximately equal numbers of positively charged ions and negatively charged electrons. Plasma consists of highly charged particles with extremely high kinetic energy. Positively charged ions swim in a "sea" of freely-moving disassociated electrons, similar to the way such charges exist in conductive metal. In fact it is this electron "sea" that allows matter in the plasma state to conduct electricity. Like a gas, plasma does not have definite shape or volume. The characteristics of plasmas are significantly different from those of ordinary neutral gases so that plasmas are considered a distinct "fourth state of matter." Unlike gases, plasmas are electrically conductive, produce magnetic fields and electric currents, and respond strongly to electromagnetic forces. Plasma is not a common state of matter here on Earth, but may be the most common state of matter in the universe. The plasma state is often misunderstood, but it is actually quite common on Earth, and the majority of people observe it on a regular basis without even realizing it. Lightning, electric sparks, fluorescent lights, neon lights, plasma televisions, some types of flame and the stars are all examples of illuminated matter in the plasma state. The noble gases (helium, neon, argon, krypton, xenon and radon) are often used to make glowing signs by using electricity to ionize them to the plasma state. Stars are essentially superheated balls of plasma.

A gas is usually converted to a plasma in one of two ways, either from a huge voltage difference between two points, or by exposing it to extremely high temperatures.