States of Matter: Definition and the Five States of Matter

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States of Matter: Introduction

The term matter is defined as anything that occupies space and has mass. The matter can neither be created nor be destroyed. Various forms of matter exist in nature and these are solid, liquid, and gas. The fourth state of matter is plasma but it does not exist in our everyday life.

A states of matter is only a way to describe the behavior of atoms and molecules in a substance.

What is States of Matter?

A substance can take on different physical forms depending on various things such as temperature, pressure, and substance`s properties. The physical form is commonly called the state of matter. The states of matter are also called phases.

There are four common states of matter and it has been described in Figure 1.

States of Matter- Definition and the Five States of Matter 1

Figure 1: The different states of matter

1. Solid State

The solid is one of the state of matter, where the molecules are tightly packed and are held together by strong forces.

The molecules in the case of solids are not able to move freely however they can vibrate at their fixed positions.

The solids have a fixed shape and size.

The rate of diffusion in solids is low and density is high.

Examples of solid include metal and ceramic bowls.

Based on the arrangement of solid molecules, the solids can further be divided into crystalline and amorphous.

(a) Crystalline Solid State

The crystalline solid state of matter is a periodic arrangement of fixed and long-range order of atoms/ molecules in all three dimensions.

Among the common examples are rock salt, sugar, metal keys, etc.

(b) Amorphous Solid State

The amorphous solid state of matter is a periodic arrangement of a short range of atoms/ molecules in all three dimensions.

Common examples are window glass, cotton candy, etc.

2. Liquid State

In liquids, the forces between the molecules are weaker than the solids.

Particles are fairly close together but can move around freely.

The liquids have an indefinite shape and can adapt to the shape of the container in which it has been kept.

The volume of liquid is fixed and the rate of diffusion in liquid is comparatively higher than that of solids.

The examples commonly include cola, coffee, tea, etc.

3. Gaseous State

This state of matter can be differentiated by low density and viscosity.

great expansion & contraction with changes in pressure and temperature, capacity to diffuse readily; and the tendency to become distributed homogeneously throughout any container.

The shape of the gas is not fixed.

The particles of gas have weak or no bonds.

The kinetic energy of gas molecules is very high as intermolecular forces are small.

The air we breathe is composed of gaseous states of many elements of which only oxygen is choosen by our body.

Plasma State

The matter of plasma is composed of atoms/ molecules, under the condition of standard pressure & temperature (STP) matter.

It has electrons that can orbit the atomic nucleus.

The shape and volume of plasma are not fixed.

If the temperature is very high, the electrons in the valence shell acquire enough kinetic energy to escape the atom. Therefore the plasma has very high kinetic energy.

The plasma produces the magnetic fields and sturdily responds to the electromagnetic field.

Plasma also possesses exclusive properties as free electrical charges cause it to be electrically conductive.

Examples of plasma are the illuminated state such as lighting, electric sparks, and some types of flames.

Phase Change

Phase changes occurs ,when the temperature or pressure change of a system takes place,.

When the temperature or pressure increases, the contact between the molecules increases.

Similarly, when the temperature decreases, it is much easier for molecules and atoms to settle into a more rigid structure.

Below represents the numerous phase changes.


– Melting

– Vaporization

– Condensation

– Sublimation

Change of State between Solid and Liquid
(a) Freezing

The method by which the substance changes from the liquid phase to the solid phase. The temperature at which any substance freezes, is called the freezing point.

For example the freezing of water to become solid ice.

(b) Melting

The process by which solid changes to liquid is called melting. The example here is when ice cubes from the freezer are placed in a warm room, the ice would absorb energy from the warmer air around them.

This absorption of energy would facilitate them to overcome the forces of attraction holding them together and enabling them to slip out of the fixed position that they held as ice.

Change of state Between Liquids and Gases
(a) Vaporization

Bubbles of water vapor form in the boiling water because particles of liquid water gain sufficient energy to completely overcome the force of attraction between them and change to the gaseous state.

Thus, the bubbles rise through the water and escape from the vessel as steam. The process of vaporization happens through two methods and that is evaporation and boiling.

The method in which a liquid boils and changes to gas is termed vaporization. The temperature at which a liquid boils. For example; boiling water to become steam, salt is recovered from seawater through this process.

(b) Condensation

When hot water interact with cooler surfaces such as the mirror, it chills and loses energy. The cooler water particles no longer have the energy to overcome the forces of attraction between them.

Together they form droplets of liquid water. This process in which a gas changes to liquid form is defined as condensation.

Example; Fog in the Air, Visible Breath in Cold Conditions, Clouding a Mirror, Steamy Rest room Mirror.

Change of state Between Solids and Gases
(a) Sublimation

The process in which solids directly change to gases is defined as sublimation. This occurs when solids absorb enough energy to overcome the forces of attraction between them.

For example; Dry ice is a case of solids that undergo sublimation, Snow and ice can sublime in the wintertime without melting, Mothballs sublime, Frozen foods sublime and ice crystals are found inside of the box.

(a) Deposition

A deposition is defined as the process in which a gas changes directly to a solid without going through the liquid state.

Examples of deposition in nature include frost forming on the ground and cirrus clouds forming high in the atmosphere, beaches, deltas, glacial moraines,sand dunes and salt domes in strictly cold temperatures form frost on windows because the water vapor in the air comes into contact with a window and proximately forms solid ice without even forming liquid water.

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