Matter is any substance with mass and volume that exists in four distinct forms; solid, liquid, gas, and plasma.The distinct forms of matter are known as ‘states of matter’ and are observable in everyday life. There are many intermediate states also to be said in existence.The component particles of matter are atoms, molecules, or ions. These constituent particles determine the states of matter. When these particles are closely packed together due to the strength of the forces between the particles, the matter takes the form of a solid. The particles in a solid state can only vibrate and cannot move freely.When a solid gets heated above its melting point, it takes the state of a liquid. Then particles have sufficient energy to move relative to each other and become mobile in the liquid form.The third state of matter is gas. While liquids are nearly incompressible fluids, gases are compressible fluids. The vast separation of component particles distinguishes gases from solids and liquids.Ice, water, and vapor are examples of the same matter in the above three states.The fourth state of matter, plasma, is not common under normal conditions on Earth.PropertiesIt is difficult to observe gases directly and they are differentiated by their physical properties like pressure, volume, the number of particles, and temperature. Examples of such elemental gases include hydrogen, nitrogen, oxygen, fluorine, chlorine, helium, neon, argon, krypton, xenon, and radon.Gases have no fixed shape or volume so can contract or expand according to temperature and pressure. This results in them occupying more space than they would in their solid or liquid state and they assume the shape and volume of their holding container.Another property of gases is the ease with which they mix with one another. Diffusion is the process of two or more gases mixing due to a large amount of space between gas molecules, forming a homogeneous mixture.Gases are scattered molecules spread across a given volume. Hence their density is low compared to their solid or liquid states. Low density allows gas particles to pass randomly and rapidly, which gives them fluidity.Molecules in gases are positioned far apart from each other due to low density which makes them compressible as well as expandable, so they fit into the shape and volume of the container which holds them.As gas molecules are highly mobile, they tend to be in constant motion resulting in pressure on the interior surface of their container. The temperature and volume of the container determine the pressure or force per unit area. Gas molecules travel from an area with high pressure to one with low pressure.TypesBased on the characteristics, properties, and structure of molecules found in gases, they are categorized into different types.Gases made up of individual atoms are referred to as ‘pure gases.‘A pure gas may contain elemental molecules, with one type of atom, or compound molecules with various atoms.The air that we breathe is made up of mixed gases and contains many pure gases.Noble gases are monoatomic gases. Sometimes also referred to as ‘aerogens’, noble gases under standard conditions contain a class of chemical elements that have similar properties.Noble gases are nearly unreactive or have very low chemical reactivity and are colorless and odorless gases.The toxicity of toxic gas is measured based on the median lethal concentration (LC50) in the air.Most toxic gases are detectable by their odor. Based on LC50 levels, toxic gas is rated as fatal, may cause serious or permanent injury, and exposure should be limited.A theoretical gas, not subject to interparticle interactions and formed of randomly moving point articles, is called an ideal gas or perfect gas.Collisions between atoms in an ideal gas are perfectly elastic.The ideal gas concept follows ideal gas law but may not apply to high-pressure situations or with lower temperatures.Non-ideal gases are called real gases, which do not obey ideal gas law.Permanent gases have a critical temperature below the range of normal human-habitable temperatures.These gases are presumed to remain in the gaseous phase permanently and cannot be liquefied by pressure.ExamplesEarth’s atmosphere is full of gases, sometimes visible to human eyes and sometimes not. We can sense the presence of some gases and not of some others. As they have weaker intermolecular bonds than solids and liquids, gas molecules are more widely separated from one another than in solids and liquids.Jan Baptist van Helmont, a physiologist, physician, and chemist from Brussels, used the word gas for the first time in the early 17th century.The first known gas was identified by him as carbon dioxide. Carbon dioxide is a colorless gas with acidic properties.One carbon atom covalently double bonded with two oxygen atoms forms carbon dioxide and its solid form is dry ice.Certain elements maintain their gaseous phase when a pure substance consisting only of atoms with the same number of protons in the nuclei is at standard pressure and temperature.Among these gases, helium, neon, argon, krypton, radon, and xenon are examples of monatomic noble gases, while hydrogen, nitrogen, and oxygen are diatomic. Fluorine and chlorine are examples of halogens.Fluorine is a pale yellow-green gas, whereas chlorine is greenish yellow at room temperature.Apart from the oxygen and carbon dioxide present in the air, we come across many other gases in our homes and our day-to-day activities.Examples of these include water vapor and cooking gas, which when stored in its liquid form is a mixture of gases such as propane, butane, and propylene. These are highly inflammable and made up of hydrogen and carbon.Fun Facts About GasesGases have always been mysterious to humans and so make us think and experiment to discover more.The atmosphere of Earth, air, protects life on Earth. This layer of gases creates pressure making liquid water remain on Earth’s surface.Dry air contains 0.04% carbon dioxide, 20.95% oxygen, and 78.08% nitrogen, amongst other gases.It also contains 1% water vapor at sea level. Water vapor around the entire atmosphere amounts to be 0.4%.Propane, containing carbon and hydrogen atoms, is a gas at standard temperature and pressure. It is used in hot air balloons compressed in its liquid form.A gas that is lighter than air is very familiar to us. Helium is used to fill balloons so they can float higher and higher. Helium is an element with a very low melting and boiling point.A binary component of nitrogen and oxygen is known as nitrous oxide and causes euphoria and hallucination and is hence named laughing gas.
Matter is any substance with mass and volume that exists in four distinct forms; solid, liquid, gas, and plasma.
