What is matter?
Matter is anything that has mass and takes up space. Both physics and chemistry study matter from different points of view. Everything around us is composed of matter, which can occur in various states.
What are the states of matter?
Matter occurs in three states, also called phases of matter:
- Solid: the atoms of solid matter are very close together, so they have a fixed shape and volume. Solids cannot be compressed; however, high temperatures increase the vibration of their particles, causing them to dilate slightly. Solids have shape memory, so if they are deformed, they tend to return to their original shape.
- Liquid: they have a fixed volume, but their atoms are less cohesive than those of solids, so their shape varies accordingly; they take the shape of the surface or container where they are located.
- Gas: their particles are not cohesive and tend to spread out, so they have no fixed shape or volume. Like liquids, their shape will depend on the container, but unlike them, gases occupy absolutely all the space available in their container. The volume of gases changes according to temperature and pressure conditions, so they can be compressed to accommodate a greater quantity in smaller containers.
These are the classical states of matter, as well as those that can most easily be observed in everyday conditions. However, as science has advanced, new states of matter have been observed in extreme or extraterrestrial conditions.
What are the new states of matter?
Plasma: basically a gas, but ionized; that is, it is composed of atoms that have separated from some of their electrons.
While it might seem that this characteristic is insufficient to consider it a distinct state of matter, in practice, plasma happens to be capable of conducting electricity, and under the influence of a magnetic field, it can form rays and filaments (example: plasma screens).
The sun and much of the universe are made of plasma.
It is a state of matter that can occur in certain materials at temperatures close to absolute zero. The condensate has no classical analogue and is considered the fifth state of matter. It is cold and dense (300 times colder than atoms had been cooled before), and scientists are sure that their atoms become immobile (known as absolute zero).
This state was predicted by Albert Einstein and Satyendra Nath Bose in 1927. It remained a theoretical state of matter for almost half a century, until physicists E. A. Cornell, W. Ketterle, and C. E. Wieman managed to develop it in the laboratory, which earned them the Nobel Prize in Physics in 2001.
How does matter change state?
Matter changes state under variations in temperature and pressure. Each of these changes is given a name:
SOLID — fusion → LIQUID
SOLID— sublimation → GAS
LIQUID— evaporation → GAS
LIQUID— solidification → SOLID
GAS— deposition*→ SOLID
GAS— condensation → LIQUID
GAS— liquefaction* → LIQUID
GAS— ionization → PLASMA
PLASMA — deionization → GAS
* Deposition may also be called reverse sublimation.
* The difference between condensation and liquefaction is that condensation is the reverse evaporation process, while in liquefaction, the change of state occurs due to an increase in pressure and decrease in temperature (as in the production of liquid nitrogen).
Each element changes its state under different conditions and circumstances, but water (and its cycle) is a good example to see and understand changes in the state of matter more easily:
Water occurs naturally in a liquid state, but you simply have to cool it enough (reaching the freezing point, 0 ºC) for it to go to a solid state (known as ice), or heat it sufficiently (reaching the boiling point, around 100 ºC) for it to become water vapor (gaseous state). Finally, condensation returns water vapor (the gaseous state) to the liquid state – water (for example, rain).
The process of sublimation (direct passage from a solid to a gas, bypassing the liquid state) is generally rarer to see in natural circumstances, but in the case of water, this can be observed as dry ice. Another rare process is that of deposition, or reverse sublimation; again, in the case of water, we can see the atmospheric phenomenon of hail.
Are there other states of matter?
There are many other states of matter. Most of them are only possible in very extreme or controlled circumstances (in a laboratory, under very specific conditions in the outside world, etc.), or have even only appeared theoretically (there are models and theories according to which such a state should exist, but its observation and study is not currently possible). Other states are considered near variations of the major states. Some of these are:
- Liquid crystal
- Strongly or weakly symmetric matter
- Quark matter (also known as strange matter)
- Degenerate matter
- Polariton superfluid
- Quantum spin liquid