The Solid State

Introduction to the Solid State

Solids constitute a large part of our lives as we utilize solids more than liquids and gases in our day to day activities. Generally a solid is defined as a substance which has rigidity, fixed shape, and size. But what makes solid different from gases and liquids? The nature of particles of matter and the binding force between them varies with solids, liquids, and gases. For Example, the particles of matter in liquids and gases are free to move inside the structure adding to its property of fluidity. On the contrary particles of matter inside solid remain stationary in their position, leading to the reason why solids don’t flow like liquids and gases.

Image 1: In the lattice, we can see how particles of matter are arranged to form solid shape

Also, the space between particles of matter in solids is quite less as compared to liquids and gases. This is the reason why solids are rigid in nature as the constituent particles are closely bound to each other. The study of solid state is all about exploring the nature, arrangement, and forces between constituent particles.
 

Solid State

Solids are substances characterized by definite shape, volume and high density. In solid state the constituent particles of matter are arranged in several patterns.The study of solid state is called solid state chemistry, also known by the name materials chemistry which explores preparation, the structure of properties of solid state materials. Solids are defined by following general properties:

• Definite Shape

• Definite Volume

• Rigidity

• High Density

• Low compressibility

• The constituent particles of matter inside solid (atoms, molecules or ions) are tightly packed together and bound by strong attractive force

Example: Electronic Gadgets, Books, Table etc all solids depict property like rigidity and have high density.

Image 2: Properties of Solids; fixed shape, volume, and rigidity

Cause of Existence of Solid State

The solid state exists because of following reasons. They are:

• Intermolecular Forces

• Thermal Energy

Intermolecular Forces

The forces between constituent particles of matter inside solid are known as intermolecular forces. The forces are attractive in nature and are responsible for holding all the particles together and making the existence of solid state possible. The constituent particles are held such that they can’t move from their position and adhere to only oscillate about their mean position. There are four types of intermolecular forces, namely:

• Dipole-Dipole forces

• London Dispersion forces

• Hydrogen bonding

• Induced-dipole forces

All the first three intermolecular forces are collectively called Van der Waals Forces and are responsible for the existence of solid.

Thermal Energy

The energy acting between constituent particles of matter in a solid is known as Thermal Energy. Thermal energy is also called Kinetic Energy and is responsible for motion of molecules inside solid lattice. Thermal energy increases with increase in temperature. And hence more the thermal energy faster will be the movement of molecules. At low temperature the value of thermal energy is low and intermolecular forces are stronger. This resists the flow of molecules and adhere them to oscillate about their mean position.

Types of Solids

On the basis of the arrangement of constituent particles solids are generally classified into distinct categories, which are:

• Crystalline Solids

• Amorphous Solids

Crystalline Solids

Image 3: Example of Crystalline Solid

The solids in which the constituent particles are arranged in a regular manner are called crystalline solids. They are also known as True Solids. In the crystalline solids, the particles of matter are arranged regularly in a three-dimensional network called A Lattice or Crystal Lattice. There are many points of a crystal lattice and each point represents a constituent particle of matter inside solids. These points are known as Lattice Points or Lattice Sites.

Example: Sodium Chloride (NaCl), Copper, Iron, Sulphur, Phosphorus etc.

Amorphous Solids

Image 4: Example of Amorphous Solid

The solids in which the arrangement of the constituent particle is irregular and not fixed are known as Amorphous Solids. Amorphous solids have a tendency to flow slowly, hence they are also known as Pseudo Solids.

Examples: Glass, Gels, Polymers etc.
 

Applications of Solid State

Solids have a number of applications in our day to day lives. Some of them are:

• NaCl, example of crystalline solid is used in cooking and preparation of several edible items

• Glass, an example of amorphous solid is used widely as a major industry component like in buildings, window panes etc.

• Polymers and gels are used majorly in maintenance industry and ensure proper functioning of electronic and mechanical equipments

• Several solids are used these days to cure certain diseases, thereby aiding the medical industries to do better

Image 5: Glass is one of the most cited examples of Amorphous Solids

There are sub topics of solid state chemistry:

• Classification of Solids

• Crystal Lattices and Unit Cells

• Close packing in crystals

• Packing Fractions

• Structure of Ionic Compounds

• Imperfections in Solids and defects in Crystals

• Properties of Solids

• Solved Problems

Related Resources

• Look here for Syllabus of  IIT JEE

• Click here to get the Past year Papers of IIT JEE

• Know how to calculate Packing Fractions of crystals. 

To read more, Buy study materials of Solid State comprising study notes, revision notes, video lectures, previous year solved questions etc. Also browse for more study materials on Chemistry here.

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The Solid State