Properties of Solids: A solid-state is simply one of the states of matter. We learned in elementary school that matter exists in three states: solid, liquid, and gas. However, as we proceed through the grades, the concepts become more complicated, and there are more things to learn. In this lesson, we will look at the notion of solid-state in a broader sense and comprehend all of the underlying terminology, such as the qualities and varieties of solids.

We will learn about the properties of solid, liquid and gas in this article. The distinct characteristics of solids distinguish them from liquids and gases. They, for example, have the ability to withstand any force applied to their surface. However, the solid-state of a molecule is heavily influenced by atomic characteristics, such as their arrangement and forces between them. Read the article to learn more about the solid state of matter.

What are the Properties of Solids?

The characteristics of solids are many. It is a form of matter that processes rigidity and, hence, possesses a definite shape and volume. According to the kinetic molecular model, solids have a regular order of their constituent particles. These particles are present in fixed positions because they are held together by relatively strong forces.

Some important characteristics of solid properties are:

1. Solids have definite mass, shape and volume.
2. Solids possess rigidity.
3. Solids are almost incompressible.
4. The density of solids is greater than that of liquids and gases.
5. Most solids become liquids when heated, and this process is known as melting. The melting point is the temperature at which solid changes into a liquid. The melting point of the solid depends upon the nature of the solid, and the melting point of the solid very widely. Usually, solids have a high density. 
6. Solids have short intermolecular distances and strong intermolecular forces.
7. Solids diffuse very slowly as compared to liquid and gases.

Changing States of Matter-Factors

The nature of the elements and their arrangement and the type of forces that hold the constituent particles together in a tightly packed arrangement determine the qualities of solids. The total effect of two opposing forces called intermolecular forces and thermal energy determines the property of a solid under particular temperature and pressure circumstances.

1. Intermolecular Forces

These are the forces existing among the constituent particles which try to keep the constituents particles close together.

The predominance of intermolecular forces results in a change from gaseous to liquid to solid-state.

2. Thermal Energy

This is the energy that the constituent particles have as a result of temperature. This energy tries to keep the constituent particles apart as it tends to make them move faster. At low, the thermal energy is relatively low. However, intermolecular forces are so strong that the particles are brought very close together. As a result, the constituent particles are stuck in fixed places, unable to oscillate around their mean positions. As a result, the material can be found in a solid-state.

The predominance of thermal energy results in the change from solid to liquid to gas.

Electrical Properties of Solids

The electrical property of a substance refers to its ability to allow the flow of current. It is quantified in terms of delocalized electrons, which are required for current conduction through a solid material.

Based on electrical conductivity, solids can be classified into three types:

1. Conductors

The solids which allow the passage of electric current are called conductors. They have conductivities in the range \({10^4}\,{\rm{to}}\,{10^7}\,\,{\rm{oh}}{{\rm{m}}^{{\rm{ – 1}}}}{{\rm{m}}^{ – 1}}.\) For example, metals have conductivities of the order of \({10^7}\,{\rm{oh}}{{\rm{m}}^{ – 1}}\,{{\rm{m}}^{ – 1}}\) and hence are the best conductors of electricity.
Conductors are of two types: Metallic conductors or Electrolytic conductors.
a.) Metallic Conductors: These are materials that allow electricity to pass through them without experiencing any chemical changes-for example, copper, aluminium, silver, etc.
b.) Electrolytic Conductors: These are the materials that allow the electricity to pass through them by undergoing chemical change.

2. Insulators

The solids that do not allow electric current passage through them are called insulators. They have  low conductivities ranging from \({10^{ – 20}}\,\,{\rm{to}}\,\,{10^{ – 10}}\,\,{\rm{oh}}{{\rm{m}}^{ – 1}}{{\rm{m}}^{ – 1}}\) For example, rubber, phosphorus, Sulphur, wood, etc.

3. Semiconductors

The solids whose conductivity lies between typical metallic conductors and insulators are called semiconductors. The conductivity of semiconductors is due to defects and impurities. The conductivity in a semiconductor ranges from \({10^{ – 6}}\,\,{\rm{to}}\,\,{10^4}\,\,{\rm{oh}}{{\rm{m}}^{ – 1}}{{\rm{m}}^{ – 1}}\)
Semiconductors are of two types:
a.) Intrinsic Semiconductors: The electrical conductivity of semiconductors increases as the temperature rises because more electrons can jump from the valence band to the conduction band. Pure substances such as silicon and germanium are called intrinsic conduction, and these pure substances exhibiting electrical conductivity are called intrinsic conductors.
b.) Extrinsic Semiconductors: Extrinsic semiconductors are those that have impurities intentionally added to them in order to make them conductive.

Magnetic Properties of Solids

The magnetic property is attributed to the magnetic moments produced by electron spin and orbital motion and their interaction with an external magnetic field. We know from the atomic structure that an electron moves in its atomic orbital around the nucleus and spins its own axis. These two types of motion give rise to the magnetic moment of an atom.

It is now well understood that the electron is a charged particle that orbits the nucleus and spins around its own axis. As a result, it can be thought of as a small current loop with a magnetic moment. As a result, each electron in a substance is associated with an orbital and spin magnetic moment.

Classification of solids concerning their magnetic properties are:
1. Diamagnetic Substances: Substances that are weakly repelled by the external magnetic field are called diamagnetic substances, and this property is known as diamagnetism. This property is caused by an induced magnetic field of the orbital electron. It is more or less in all substances, but it is more pronounced in materials like \({{\rm{H}}_{\rm{2}}}{\rm{,\;KCl,\;NaCl\;and\;Ti}}{{\rm{O}}_{\rm{2}}}\;\) in which all the electrons have paired spin.
2. Paramagnetic Substances: Substances that are attracted by the external magnetic field are called paramagnetic substances, and this property is known as paramagnetism. It is caused by the spin and orbital angular momentum of electrons. Paramagnetism is shown by all those solids in which atoms, ions or molecules have unpaired electrons. \({{\rm{O}}_{\rm{2}}}{\rm{,\;KMn}}{{\rm{O}}_{\rm{4}}}{\rm{,\;Na,\;K,\;C}}{{\rm{u}}^{{\rm{2 + }}}}{\rm{,\;F}}{{\rm{e}}^{{\rm{3 + }}}}.\)
3. Ferromagnetic Substances: Ferromagnetic substances are those that exhibit permanent magnetism even in the absence of a magnetic field. This property is caused by particles arranged on lattice and electrons with parallel spins. Iron \(\left( {{\rm{Fe}}} \right)\) cobalt \(\left( {{\rm{Co}}} \right)\) and nickel \(\left( {{\rm{Ni}}} \right)\) are ferromagnetic elements.
4. Anti-ferromagnetic Substances: Anti-ferromagnetic substances are expected to have paramagnetism or ferromagnetism based on the magnetic moments of the domains but have zero net magnetic moments. This property is caused by particles arranged on two lattices, let’s call them \(A\) and \(B,\) with spins on \(A\) antiparallel to those on \(B.\) This causes magnetic moments on lattice \(A\) to cancel out magnetic moments on lattice \(B.\) The materials like \({\rm{MnSe,\;KMnF}}{{\rm{e}}_{\rm{3}}}\) are anti-ferromagnetic.
5. Ferrimagnetic Substances: Substances that are expected to possess large magnetism based on the magnetic moments of the domains but have small net magnetic moment are called ferromagnetic substances. The particles on interpenetrating lattices cause this magnetic property with an unequal number of electrons and with antiparallel spins. This represents a situation with a net magnetic moment. \({\rm{FeO}}{\rm{.F}}{{\rm{e}}_{\rm{2}}}{{\rm{O}}_{\rm{3}}}{\rm{\;}} \equiv {\rm{F}}{{\rm{e}}_{\rm{3}}}{{\rm{O}}_{\rm{4}}}\) is an example of ferrimagnetic material.

Properties of Solid Materials

The important properties of solid materials are:

Properties of Solid, Liquid and Gas

The properties of solid-liquid gas are:

Property	Solid	Liquid	Gas
Shape and Volume	Solids have a definite volume and a definite shape.	Liquids have fixed volume but have no fixed shape. They take the shape of the container, but they do not fill it.	Gases have neither a fixed volume nor a fixed shape. Instead, they take shape and volume of the container, and they fill the container.
Density	Solids have high densities.	Liquids have moderate to high densities. However, they are generally less dense than solids.	Gases have very low densities, and they are very light.
Compressibility	Solids are rigid and are not compressible.	Like solids, liquids cannot be compressed much.	Gases are easily compressible.
Interparticle Forces of Attraction	The interparticle forces of attraction are most vital in solids.	Interparticle forces of attraction in liquids are weaker than those in solids but stronger than those in gases.	In gases, the interparticle forces of attraction are the weakest.
Fluidity	Solids do not flow.	Liquids generally flow easily.	Gases flow more easily.
Diffusion	Solids do not diffuse	Liquids can diffuse more than solids.	Gases have a strong tendency for diffusion.
Spreading	Solids stay where they are placed.	The Liquids can be poured into other containers.	Gases spread out quickly.

Summary

From this article, we can conclude that solids have a definite shape and a definite volume. Most solids become liquids when heated, and this process is known as melting. The total effect of two opposing forces called intermolecular forces, and thermal energy determines the property of a solid under a particular temperature and pressure.

FAQs on Properties of Solids

Q.1: What are the six properties of solids?
Ans: Solids have definite mass, shape and volume., Solids have rigidity, are incompressible, have a higher density, and have a strong intermolecular force.

Q.2: Which of the following are the common properties of solid
A. They have a definite shape
B. They have a definite volume
C. They have fixed boundary
D. All the above
Ans: D

Q.3: What are the properties of solid shapes?
Ans: Cuboid, sphere, cylinder, cone, etc. are the properties of solid shapes.

Q.4: What are the properties of solid materials?
Ans: The important properties of solid materials are:
1. Mechanical
2. Thermal
3. Electrical
4. Magnetic
5. Deteriorative

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