What are the different states of matter, and how do they change?
Matter can exist in several different states, also referred to as phases. The four fundamental states of matter observable in everyday life are solid, liquid, gas, and plasma. Beyond these, there exist other exotic states of matter, like Bose-Einstein condensates, fermionic condensates, and quark-gluon plasma, among others.
Solid
In a solid, particles (atoms, molecules, or ions) are closely packed together. The forces between these particles are strong enough that they cannot move freely but can only vibrate. As a result, a solid has a stable, definite shape, and a definite volume. Solids can only change their shape under force, as when broken or cut.
Liquid
In a liquid, particles are still closely packed, but have enough energy to move past one another. Liquids have a definite volume, but their shape can change. They conform to the shape of the container they are placed in. The particles in a liquid are not as closely packed as those in a solid; they move freely, allowing liquids to flow.
Gas
In a gas, particles have a lot of energy and are far apart. The forces between particles are not strong enough to keep them together, giving a gas the ability to expand infinitely and fill any container. Gases have neither a definite volume nor shape and can be compressed.
Plasma
Plasma is a state of matter similar to gas, but the particles are electrically charged. It’s found in stars, and it’s the most common state of matter in the universe.
Changes in states of matter are caused by changes in thermal energy – that is, heat. The change from solid to liquid is called melting, from liquid to gas is vaporization, from gas to liquid is condensation, and from liquid to solid is freezing. There’s also sublimation (solid to gas) and deposition (gas to solid).
Beyond the classical states
At extremely low temperatures, quantum mechanical effects become significant and we can observe other states of matter, like Bose-Einstein condensates, where certain particles condense into the lowest energy state, and superconductors, where electrical resistance disappears. On the other hand, at extremely high temperatures and pressures, we can create a quark-gluon plasma, where protons and neutrons dissolve into a fluid of quarks.
The understanding of states of matter continues to evolve as our ability to create extreme conditions in the lab progresses, and as we encounter exotic conditions in different astrophysical settings. Each new state of matter gives us a deeper understanding of the fundamental behavior of particles.
