States of Matter

In general, states of matter are described in terms of qualities that can be seen or felt. A solid is matter that feels hard and has a fixed shape; a liquid is matter that feels wet and has a fixed volume but not a fixed shape. A gas is defined as matter that can change shape and volume. Although some introductory chemistry textbooks refer to solids, liquids, and gases as the three states of matter, higher level textbooks recognise plasma as the fourth state of matter. Plasma, like a gas, can change volume and shape, but unlike a gas, it can also change electrical charge.

The states of matter

Solid

Because the molecules that make up a solid are packed closely together and move slowly, a solid has a definite shape and volume. Solids are frequently crystalline; crystalline solids include table salt, sugar, diamonds, and a variety of minerals. When liquids or gases cool, solids form; ice is an example of a cooled liquid that has solidified. At room temperature, other examples of solids include wood, metal, and rock.

Liquid

A liquid has a fixed volume but conforms to the shape of its container. Water and oil are two examples of liquids. When gases cool, they may liquefy, as water vapour does. As the molecules in the gas slow down and lose energy, this happens. When solids heat up, they can liquefy; molten lava is an example of a solid rock that has liquefied as a result of intense heat.

Gases

A gas has neither a fixed volume nor a fixed shape. Some gases can be seen and felt by humans, while others are intangible. Air, oxygen, and helium are examples of gases. The Earth’s atmosphere is composed of gases such as nitrogen, oxygen, and carbon dioxide.

Plasma

Plasma has neither a fixed volume nor a fixed shape. Plasma is commonly seen in ionised gases, but it is distinct from a gas due to its unique properties. The presence of free electrical charges (charges that are not bound to atoms or ions) causes the plasma to be electrically conductive. Heating and ionising a gas can result in plasma formation. Stars, lightning, fluorescent lights, and neon signs are all examples of plasma.

Characteristics of states of matter

• Solid matter has a well-defined body with its own constant volume and shape. This is due to the fact that the particles of solid substances form rigid, narrow structures that provide resistance to external forces.

• They are resistant to fragmentation and have little to no fluidity. They have high cohesion as well as “shape memory,” which means that when subjected to force, they tend to elastically regain their original shape.

• Liquid matter does not have its own shape; instead, it takes on the shape of the container in which it is found.

• When matter is in a gaseous state, it is referred to as “gas.” Its particles are loosely connected, spread throughout the surrounding space, and have a very slight attraction to one another.

• Matter has a very low density in a gaseous state because its particles are in relative disorder, moving very quickly in space, and can float due to their low response to gravity.

• A liquid has a fixed volume but conforms to the shape of its container. Water and oil are two examples of liquids. When gases cool, they may liquefy, as water vapour does. As the molecules in the gas slow down and lose energy, this happens. When solids heat up, they can liquefy; molten lava is an example of a solid rock that has liquefied as a result of intense heat.

• A gas has neither a fixed volume nor a fixed shape. Some gases can be seen and felt by humans, while others are intangible. Air, oxygen, and helium are examples of gases. The Earth’s atmosphere is composed of gases such as nitrogen, oxygen, and carbon dioxide.

Changing  states of matter

Evaporation

It is the process of slowly and gradually converting liquid matter into gas through the addition of heat. This additional energy further separates its loosely bound particles, allowing them to become gaseous and rise (having a lower density than air ).

Boiling 

It is the process by which a liquid turns into vapour when its temperature rises above its boiling point (temperature at which the vapour pressure of the liquid equals the pressure around the liquid). There is a distinction to be made between evaporation and boiling. Evaporation occurs at any temperature; simply raising the temperature of the liquid causes it to slowly transition into the gas phase. Boiling, on the other hand, is unavoidable when the temperature of a liquid exceeds its boiling point.

Sublimation

It is the process of directly converting solid matter to gas without passing through the liquid state. It normally necessitates very specific pressure conditions, such as ice or snow in the mountains, which cannot melt into a liquid due to the low temperature at which it is found, but can go straight to vapour.

Solidification

It is one of the inverse processes of fusion, meaning it converts liquid matter to solid matter. It is commonly accomplished by increasing the pressure of the liquid, i.e., compression, which slows the movement of the particles and allows them to attract each other more strongly.

Freezing

It is the process of converting a liquid into a solid by lowering its temperature below its freezing point (the temperature at which the liquid freezes due to the extraction of heat energy).

Condensation and liquefaction

They are two similar processes in which matter in a gaseous state transforms into matter in a liquid state. The difference between the two is that the first, condensation, occurs when a gas comes into contact with a colder surface, such as the dew that forms on the windows in the early morning. The modified factor in the second case, on the other hand, is pressure, as in the case of cooking gases compressed in drums.

Conclusion

Beyond solids, liquids, and gases, there are many other states of matter, such as plasmas, condensates, superfluids, supersolids, and strange matter. Kinetic Molecular Theory describes how the energy of atoms and molecules results in various states of matter. Scientists are constantly discovering new states of matter! Other states of matter include superfluid, Bose-Einstein condensate, fermionic condensate, Rydberg molecules, quantum Hall state, photonic matter, and dropleton, in addition to the four main states of matter.