# solid state

2022

We explain what the solid state is and what are the physical characteristics of this state of matter. Examples of solids.

Thanks to cohesion, solids have clear boundaries and a volume of their own.

## What is the solid state?

A solid state is called one of the four essential forms in which matter is presented, together with the liquid, the soda and the plasmatic. These forms are called states of matter aggregation.

Matter in the solid state (or simply solids) is characterized by a specific arrangement of its particles, based on very rigid and strong links, which translates into a very well defined physical structure. This occurs due to the cohesion forces between the particles, responsible for maintaining the shape and the volume solid, and to give it a certain margin of hardness and endurance.

However, these forces can be overcome through physical processes of phase change, being able to convert a solid into a liquid or a gas. Such processes are called:

• Fusion. Physical process that consists of applying heat to a solid to increase your temperature until you get to your melting point (temperature at which the solid passes to the liquid state, at this temperature the solid and the liquid coexist in thermodynamic equilibrium). When the temperature exceeds this point, the energy of the solid increases enough to break the cohesion between its particles and causes the phase change. Melting also depends on the pressure to which the solid is subjected.
• Sublimation. Physical process by which a certain solid passes directly into the gas phase, without first passing through the liquid phase. This can be achieved by manipulating the temperature conditions and Pressure specifically for each solid, thus avoiding going through the liquid phase before reaching the vapor. An example of this is the sublimation of solid iodine (I), where a violet-colored gas is produced.

## Solid state physical characteristics

Matter in solid state has the following characteristics:

• Rigidity. In general, solid matter resists deformation. For example: kinks, kinks, splits. Only if their resistance is overcome, the solids change shape (permanently or temporarily, depending on their elasticity).
• Incompressibility. Unlike gases and liquids, solids cannot be compressed, that is, their particles can no longer be together. Instead, when subjected to extreme compressive forces, they tend to fracture or break down into smaller pieces.
• Hardness. In general, solids are resistant to being penetrated by other solids, even to scratching their surface. This is known as hardness, the physical strength against the action of other solids. The hardest known matter is diamond.
• Fragility. Solids can be broken into smaller pieces.
• Elasticity. Contrary to brittleness and hardness, elasticity is the ability of certain solids to undergo a momentary deformation, under the action of a force, and then return to their original shape once the action of said force has ended. Elastic materials have a shape memory that allows them to return to their previous disposition.
• High density. Most solids have a density relatively high because the particles that compose them are very close together.
• Malleability. Some solid bodies have the capacity to be worked by deformation. Due to this property, thin sheets of a material can be obtained without breaking.
• Defined shape. Being rigid, solids have definite shapes and do not flow like liquids and gases.

## Solid state examples

Some examples of matter in solid state are:

• The metals. With the sole exception of mercury (Hg), metals at room temperature retain their solidity and hardness due to metal links between his atoms. However, if they are given enough heat (as in forges or foundries), metals flow like liquids and can take other forms.
• The ice. Liquid water, when brought to its freezing point, that is, when it is withdrawn caloric energy Until it reaches 0 ºC, it crystallizes and turns into ice, a transparent and solid substance.
• The stones. Composed of minerals and calcareous or sedimentary elements, the stones that we find on any road are the clearest example of possible solidity on the planet.
• The concrete. Result of the union of materials such as gravel, water and cement in powder, first as a wet paste and then as an extremely hard matter when drying, it is used daily in the industry of the construction.
• The bones. Mineralized with calcium taken from our diet, the bones of our body or the body of any vertebrate animal They are the ones that provide the greatest solidity to the body.
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