States of matter aggregation

The way in which the constituents of matter are grouped is known as states of aggregation of matter. There are four states of matter: solid, liquid, gas, and plasma.

Solid state

The solid state is characterized by maintaining volume and shape. The solid particles are held tightly together preventing their internal movement .

Solids can be classified as crystalline or amorphous depending on the pattern in which their particles are arranged. A crystalline solid shows a regular repeating pattern. In an amorphous solid, the three-dimensional arrangement of the particles is irregular.

Left: The structure of table salt (sodium chloride) is typical of a crystalline solid. Right: Glass is a classic example of an amorphous solid.

Liquid state

The liquid state is characterized by maintaining volume, but its shape is that of the container that contains it. Liquid particles are held together but can move . Also, liquids have the ability to flow.

Fluid fluidity depends on several factors, such as intermolecular forces, particle size, and temperature. Honey, when heated, is more fluid (less viscous) than at room temperature.

Gaseous state

The gaseous state is characterized by having variable volume and shape. A gas consists of small particles in constant motion and more separated , independent of each other.

The behavior of a gas under different conditions can be predicted according to the gas laws. Thus, an ideal gas is one that complies with the gas laws. At low temperatures and / or very strong pressures the gas laws lose validity.

The water when it boils turns into gas.

See also Gas laws

Plasma state

Plasma is a gas that has been ionized . What does this mean? A gas that receives enough energy so that its electrons escape to its atoms or molecules. Matter in the plasma state has a variable shape and volume.

Plasma contains ions and electrons that move freely. In the universe, visible matter is predominantly in the plasma state. A classic example of a plasma state is lightning that we see during storms.

Phase transitions of states of matter

The different states of matter can change from one state to another depending on changes in temperature and pressure. The measurement of the external conditions in which this transformation occurs is what is called phase transition.

Phase changes


It is the phase change from solid to liquid state, like when ice (solid state of water) melts.


It is the phase change from liquid to solid state. Ice creams are mostly solid states of fruit juices (liquid state).


When a solid goes directly to the gaseous state, it is called sublimation. We can see this change when dry ice, which is nothing more than carbon dioxide in the solid state, heats up and turns into gas.

Crystallization or reverse sublimation

It is the change from gas to solid. This is the mechanism by which clouds (gas) transform into snow (solid) without going through the liquid state.

Boiling or vaporization

When a substance in a liquid state passes into a gaseous state. For example, a liquid is transformed into a gas by heating it to the boiling point.


When a gas turns into a liquid, it is said to have condensed. The water we see on the pot lids when we are cooking originates from the water vapor that comes out of the food.


There are materials that share characteristics of two states of matter. A good example is the liquid crystals we get from watches, calculators, and computers.


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