Aggregate state of matter

The state of matter has characteristic qualities. The possibility or lack of probability of preserving form and volume, the existence or absence of short-range and long-range order, etc. is an "aggregate state".

When the aggregate shape changes, sudden changes in density, entropy, free energy, and other physical properties can occur.

Substances can be in three basic states: gaseous, solid and liquid. But not everyone is able to transform into each of them. For some, only two or one aggregate state is characteristic.

The gaseous form of matter is characterized by weakly bound or unbound particles, whose kinetic energy is several times greater than the potential energy of their interaction. In view of this, the particles have freedom of movement and completely fill the container in which they are, acquiring its shape.

The substance in liquid form has very mobile particles, between which there are small gaps. Its density exceeds the density in the gaseous state. The fluid is fluid.

Solid bodies are characterized by the stability of the shape and the definite thermal motion of the atoms, caused by their oscillation. Comparatively with the interstices between atoms, their amplitude of oscillation is insignificant. For example, the aggregate state of iron is solid. It has a stable form. Loose, but solid substances also belong to this group. Some people do not know what kind of aggregate state of sugar or salt. The answer is: "Solid".

Still distinguish such states as polymorphism (more than two polymorphic modifications) and plasma (completely or partially ionized gas).

All simple substances or chemical compounds have one form of liquid state and one - gaseous (with the exception of liquid crystals).

But the solid state of the same substance can have two or more modifications, which differ in properties and internal structure. The existence of several forms of the solid state of a particular compound or simple material has become known as "polymorphism."

The relative stability of a particular modification or phase is affected by environmental conditions: pressure and temperature. The aggregate state and the polymorphic form of the substance depend on their indices.

The process of transition from liquid to gaseous form is called vaporization. And if the vapor is produced only from the surface of the liquid - this is called evaporation. The transformation of matter from the gaseous state back to liquid is called liquefaction.

Sublimation (sublimation) refers to the transformation from solid to gaseous state, and the reverse process is called "desublimation". Sublimation can be considered on the example of freezing of window panes in the room, falling on the ground frost and other phenomena of nature.

The process of transformation of the gaseous form into liquid (liquefaction) or solid (desublimation) is defined as a single concept - condensation of steam. On this basis, such a state is considered as condensed.

The transition to a liquid form of a solid is called melting, and the reverse transformation is solidification, and under the influence of low temperatures, by freezing. The transformation of the modification of a solid form into another is called "polymorphic transformation" (transition).

While the aggregate state of a substance changes or a polymorphic transformation takes place, heat is released or absorbed. This happens, for example, during sublimation, evaporation, melting, evaporation, etc.

By whether heat is absorbed or released, we can draw conclusions about the stability of the polymorphic form or the aggregate state of the substance under various temperature conditions. Forms in which the transition is accompanied by heat absorption are more stable at high temperatures. And low temperatures are more suitable for those in which the transition is accompanied by the release of heat. Evaporation and melting occur in the presence of heat absorption, which is why the liquid state is much more stable than the solid state at high temperatures. And in a medium with a higher temperature, the gaseous form will be more stable than the liquid form.