Solid State

One of the states of matter is referred to as “solid-state.” We learned in elementary school that matter exists in three states: solid, liquid, and gas. However, as we proceed through the grades, the concepts get more complicated and there are more things to learn. In this lesson, we will look at the notion of solid-state in a larger sense and comprehend all of the underlying concepts, such as the qualities and varieties of solids.

Solids have distinct properties that 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 compound is heavily influenced by atomic properties such as their arrangement and the forces acting between them.

Physical and Chemical Properties Of Solids

• Solids are incompressible, which means that the constituent particles are placed close to each other, resulting in little space between the constituent particles.
• Solids are inflexible. This is because there isn’t enough space between the constituent particles, which causes it to be hard or fixed.
• Solids have a fixed mass, volume, and form, resulting in a compact arrangement of component particles.
• Molecules have a small intermolecular distance. As a result, the force between component particles (atoms, molecules, or ions) is extremely strong.
• Particles in the system can only fluctuate about their mean locations.

Chemistry of Solids

The study of the structure, characteristics, and synthesis of solid materials is known as solid-state chemistry. It is also known as materials chemistry at times. More importantly, in solid-state chemistry, we investigate the idea of a compound at a deeper level. It essentially aids us in understanding the molecule from the molecular to the crystal structural levels.

Solid State Types

Solids are categorized into two categories based on the arrangement of component particles:

Solid Crystalline State

Crystalline solids are ones with regular geometry. There are precise configurations of particles (atoms, molecules, or ions) across the 3-dimensional network of a crystal in a long-range order in such substances. Sodium chloride, quartz, diamond, and other minerals are examples.

Crystalline Solids’ Properties:

• Crystalline solids have a precise melting point and begin to melt at a certain temperature.
• Crystalline solids have fixed shapes and characteristic particle groupings.
• They have cleavage property, which means that when cut with the edge of a sharp instrument, they split into two pieces and the newly formed surfaces are smooth and plain.
• They have a distinct heat of fusion (amount of energy needed to melt a given mass of solid at its melting point).
• Crystalline substances are anisotropic, which implies that their physical characteristics, such as electrical resistance or refractive index, change when measured in various directions inside the same crystal.
• True solids are crystalline solids.

Crystalline Solids and Their Subtypes

Crystalline solids are further categorized into four types based on the nature of intermolecular forces or chemical bonding. They do,

• Molecular Solids
• Solids with an ionic charge
• Solids made of metal
• Solids with covalent bonds
• Molecular solids

Molecules are the component particles of molecular solids. They are further classified into three types:

• 1. Non-Polar Molecular Solids

These solids are made up of molecules or atoms that are joined together by a non-polar covalent connection. Atoms or molecules are kept together by weak dispersion forces or London forces.

• Non-polar solids have a mushy physical character.
• They are insulators because they do not conduct electricity.
• They are very brittle and have a very low melting point.
• Examples are H₂, Cl₂, I₂, and so on.

 

• 2. Polar Molecular Solids

These solids are bound together by polar covalent bonds, whereas the atoms/molecules are kept together by dipole-dipole interactions that are considerably stronger.

• The physical nature is soft, and the majority of them are at room temperature gases or liquids.
• They are non-conductive and have a greater melting point than non-polar molecular solids.
• Examples include HCl, SO₂, NH₃, and others.

 

• 3. Molecular Solids with Hydrogen Bonds

Polar covalent connections containing Hydrogen, Fluorine, Oxygen, and Nitrogen atoms exist in the solids. Strong hydrogen bonding holds molecules together in these solids.

• Such solids have a hard physical character.
• They are not electrically conductive.
• At room temperature, these substances are either volatile liquids or soft solids.
• They have a rather low melting point.
• Example: Water (ice)

Ionic Solids

Ions are the component particles of ionic solids. These are created by strong Coulombic forces arranging cations and anions.

• These are naturally hard and fragile.
• Ionic solids are insulators in the solid state but conductors in the molten and watery states.
• They have a rather high melting point.
• Examples include NaCl, MgO, ZnS, and others.

Metallic Solids

Positive metal ions swimming in a sea of delocalized electrons These electrons are distributed uniformly across the crystal.

• They are responsible for enhanced electrical and thermal conductivity due to the presence of free and mobile electrons.
• They conduct electricity in both the solid and molten states.
• These solids have a rigid physical character, yet they are bendable and ductile.
• Their melting point is higher than that of ionic solids.
• Fe, Cu, Ag, Mg, and other elements are examples.

Network Solids or Covalent Solids

A broad variety of nonmetal crystalline solids generate covalent bonds between nearby atoms throughout the crystal, resulting in the formation of a huge molecule or enormous molecules.

• These solids, which are carbon isotopes, are hard like diamond and soft like graphite.
• They are insulators, as is the diamond, however, because to free electrons, graphite conducts electricity and acts as a conductor.

Amorphous Solid State

Amorphous solid-state solids have the properties of rigidity and incompressibility, but only to a limited extent. They lack a distinct geometrical form and a wide variety of order. Glass, rubber, plastic, and other materials are examples.

Amorphous Solid Properties

• Amorphous substances soften progressively across a temperature range and may be shaped into various forms when heated.
• Amorphous solids are pseudo solids or supercooled liquids, which means they move very slowly. Amorphous solids have an irregular form, indicating that the component particles do not have a particular geometry of arrangement.
• Uneven surfaces are generated when amorphous materials are cut with a sharp edged instrument.
• Amorphous solids lack a particular heat of fusion due to the irregular arrangement of the particles.
• These substances are isotropic in nature due to the random arrangement of particles, which means that the value of any physical property would be the same in any direction.

FAQs:

Q. Why do we study solid-state?

ANS: Our readers will be aware, as scientific students, that the cosmos is made up of matter and energy. The term “matter” refers to everything that has volume and takes up space. In the world, matter exists in three different states, one of which is the solid-state. Solids, which differ from liquids and gases in their characteristics, play a significant role in our daily lives. We come into contact with solids on a regular basis, therefore understanding their qualities is essential if we are to use them effectively in our activities.

Q. What is a solid’s shape?

ANS: Solids may be found in a variety of forms and sizes around the world. If we glance around, we may see a variety of solids. The sole precise and defining condition for solids is that their forms and sizes are fixed. They do not alter with the passage of time. This is due to the extremely strong and inflexible chemical connections that exist between the component particles of a solid. Because of the presence of these strong connections, they have a set volume as well as a definite form.