Gas: The simplest of all States of Matter

What is Gas?

Gas is the state of matter in which the particles are far apart, fast-moving and not organized in any particular way.

Gas particles have no interparticle attractive force between the particles which are separated from each other by much greater distances. It has neither a definite volume nor a definite shape.

Matter is everywhere: we are made of matter, the pencils you’ve used are made of matter, the water you drink is made of matter, the air we breathe is also a form of matter (gas). If matter didn’t exist, nothing would. If we matter ourselves, how would we exist if matter did not? Without air, how would we breathe? This dependence of humans on air makes the gaseous state of matter, extremely important to us.

Three States of Matter

Three States of Matter – Solid, Liquid & Gas

The atmosphere is a mixture of gases such as oxygen, carbon dioxide, nitrogen, ozone, water vapour, etc. The gaseous state is the simplest of all states of matter, but only 11 gases in the periodic table behave as gases under standard temperature and pressure conditions ( STP i.e. 1 atm. and 273K). These are Helium, Neon, Argon, Krypton, Xenon, Radon, Hydrogen, Nitrogen, Oxygen, Fluorine and Chlorine. These gases are called pure gases.

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Physical Characteristics of Gases

  • Gases have a lower density and are highly compressible as compared to solids and liquids.
  • They exert an equal amount of pressure in all directions.
  • The space between gas particles is a lot, and they have high kinetic energy.
  • The inter-molecular forces between these gas particles are negligible.
  • These particles move at high speeds in all directions and hit each other, thus causing the gas to spread throughout the container they are kept in, evenly. This also causes them to exert pressure on the walls of the container.
  • So, gases take the volume and shape of the container.


While a real gas has negligible inter-molecular forces of attraction, an ideal gas has zero inter-molecular forces of attraction because the molecules of an ideal gas move so fast and they are so far away from each other that they do not interact at all. There is no ideal gas that exists naturally. However, gases behave most ideally at high temperatures and low pressure conditions. The behavior of gases is governed by certain laws.


1. What is meant by the gaseous state?
Ans: Gas is a state of affairs that does not have a fixed shape and a fixed size. Gasses have lower densities than other material conditions, such as solids and liquids. Among particles, there is a lot of empty space, which has a lot of kinetic energy.

2. Is cloud a gas?
Ans: Water vapor and dry air are the invisible component of clouds you can’t see. Most of the atmosphere is pure air with which the transparent water vapor is combined and the very small drops of water and ice crystals are suspended in. A cloud is a gas, water, and solid mixture.

3. What are gasses used for?
Ans: It uses the most natural gas as an oil. Around 30 percent of the nation-wide energy consumed was derived from natural gas in 2012[1 ]. It was used to generate electricity, energy, fuel, heat water, bake food, power industrial furnaces and even run air conditioners.

4. What gases are in the air we breathe?
Ans: In addition to oxygen, the air we breathe is made up of many other things! Only about 21 percent of air is made up of oxygen. Approximately 78 percent of the air you breathe is a gas called nitrogen. Other gases such as argon, carbon dioxide, and methane also have tiny amounts.

5. Why Carbon dioxide is a gas?
Ans: Since their chemical compositions are different, the reason carbon dioxide is a gas and silicon dioxide is solid. Carbon dioxide is a circular structure with two carbon-oxygen double bonds. It is a small, non-polar molecule with only weak molecular bonds. So it is a gas.

To know more about gases and Boyle’s Law, Charles’ Law, Gay Lussac’s Law, and Avagadro Law, visit our YouTube channel or download Byju’s- The Learning App.

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