What are the States of Matter? 

The substance that constitutes everything in the universe is known as matter. Matter comprises atoms which in turn are composed of electrons, protons, and neutrons. Different atoms combine together to give rise to molecules that act as a foundation for all kinds of substances. There are five states of matter based on their energies of attraction, namely solid, liquid, gases, plasma, and BEC (Bose-Einstein condensates). 

States of Matter 

The matter can be found in three specific physical state in most of the environments and they are solid, liquid and gas. However when subjected to extreme conditions a matter can be present in forms like plasma, neutron stars or Bose-Einstein condensates. The matter present in the universe is mostly present in the hot plasma form that can be found as dense stars or interstellar phase. 

The states of matter were originally characterized on the basis of their mass compositions based on their dimensional distinctions. The matter in the solid-state is the state in which a substance retains its defined volume and structure; fluid is the condition in which substances adapt to the container form but differing in volume a little whereas gas is the state in which material takes volume and shape of any container. All of these three states of matter are observed to directly transform into any one of the remaining other states of matter. 

Solid 

A substance in a solid state will have its particles held extremely tightly such that the force among the particles present will not allow the substance to move but instead will allow it to only vibrate. As a consequence a solid has a strong, certain structure and a specific volume. Solids do not change its shape easily it only undergoes a change in shape when it is subjected to external forces resulting into its breakage. Particles present in crystalline solids are routinely wrapped in an orderly, repetitive sequence. Crystal structures can be found in several different form and more than one structure is possible for the same material. This can be understood well with the example of iron which has a cubic body-centered structure below 912°C and a cubic face-centered structure between 912 and 1394°C. 

Liquid  

A liquid is the state of matter where the fluid form of substance takes the shape of the container with an almost unchanged pressure-independent to its volume. If temperature and pressure are stable, the volume is specific (not changing). As the material in the solid state is heated past its freezing point, the pressure is more than the triple point of the material it gets converted into liquid state. Unlike solid state of matter the intermolecular forces enable the substance to move in liquid state by being loosely connected to each other. This allows liquid to take the structure of the container and not specific to any one structure. The highest temperature at which the liquid exists is known as the critical temperature of that particular liquid. A liquid through the process of evaporation can be transformed into gas state by boiling it at a constant pressure or by reducing pressure while keeping the temperature constant. 

Gas 

Gas molecules can travel easily and rapidly due to their low intermolecular associations, or sometimes no intermolecular association altogether. As a result, it not only takes the shape of the container but extend further into filling the container completely. Gas molecules have minimal intermolecular forces or zero intermolecular forces as observed in ideal gas as a result of a high kinetic energy, which distributes the molecules too far apart such that the average spacing between the molecules is higher than the size of the molecules themselves. 

Any gas may also be considered as vapor below its critical temperature. Without cooling, a vapor may be liquefied by compression. It may also exist with liquid or solid equilibrium, where the gas pressure correlates to the liquid's vapor pressure or solid. 

The gas can also occur in the state called Supercritical fluid (SCF) where the temperature and gas pressure is above the critical pressure and temperature. The difference between gas and liquid ceases to exist in this condition. The supercritical fluid has all the physical features of gas but its high density gives it solvent properties in some situations. In many applications, this can be helpful such as in the processing of decaffeinated coffee, for example, supercritical carbon dioxide is used to remove coffee. 

Plasma  

On Earth plasma is not a normal state of substance but it is considered to be the most widespread form of matter found in the universe. It is believed that stars are nothing but mostly superheated plasma balls. Plasma is composed of intensely charged, incredibly high-kinetic energy particles. Sometimes the noble gasses such as helium, argon, neon, xenon, krypton and radon are used to generate vivid, glowing signals by ionizing them into their plasma state. 

Bose-Einstein Condensate (BEC) 

This state of matter is the latest invention in the study of matter. It was invented by scientists Eric Cornell and Carl Weinman, Colorado in 1995. Using a combination of lasers and magnets a sample of  rubidium was cooled to various degrees of absolute zero. In the absence of transfer of kinetic energy between the molecules the atoms tend to stick together with such that there is no longer any individual atoms, instead, it has a single "super-atom." 

A BEC is used to macroscopically analyze quantum mechanics. Light tends to be slowing across a BEC, which helps physicists to research the particle paradox or wave. A BEC also holds many features that flow in without pressure in a superfluid or in a fluid. BECs are often used to mimic situations that occur in black holes. 

Change in Phase 

A change in the physical state of a substance is often observed when energy is either added to the substance or removed. One of the most common examples which we observe on daily basis is the change in the state of water. When we add heat, water gets converted into vapor phase whereas when we remove energy from it, it gets converted into ice. 

Freezing and Melting  

When heat is added to a solid, it vibrates quicker and travels further more. The solid begins to melt and become a liquid as the material exceeds a certain temperature and pressure mix, its melting point. Many liquids compress after freezing. However, as water freezes to ice, this leads to a further isolation of molecules and density reduction, and ice thus floats away upon surface of water. Freezing and melting points can be altered with the inclusion of few materials, such as salt in water. For example, applying salt to snow decreases the temperature at which freezing of water occursenabling driving safer under extreme conditions. 

Sublimation  

The mechanism is regarded as sublimation whenever a solid is transformed straight into a gaseous form without passing into a fluid phase. This can happen either by increasing the sample temperature quickly above the boiling point of the sample also known as flash vaporization, or by cooling the specimen under circumstances of vacuum to sublimate the water in the product and to eliminate it from the sample. 

Vaporization 

The transformation of the liquid into a gas that can be achieved due to either evaporation or boiling is called as vaporization. 

Condensation

Condensation is the process when a gas loses its energy and gets converted into a liquid phase. The most common example is water vapor which condenses into water. 

How do the States of Matter Exist in Nature and Impact your Daily Life? 

State of matter is very important in our daily as everything is made up of matter. For example, the food we consume is made up of atoms and molecules and food is important for our existence. 

Common Mistakes 

The common misconception about condensation is that water droplets present on the outer surface of a container is due to water seeping out or passing through the walls of container but the truth is water vapor which is formed turns into droplets once they encounter a cooler surface of the container. 

Context and Applications

This topic is significant in the professional exams for both undergraduate and graduate courses, especially for Bachelors and Masters in Physics. 

Practice Problems

Describe the change of state during the following process and also state whether the process is exothermic or endothermic  

1. Vaporization 

2. Sublimation 

Solution:

1. vaporization is transformation of liquid into gaseous phase and it is an endothermic reaction 

2. sublimation is conversion to solid to the gas phase and it is an endothermic reaction