Properties of Materials:

1. Physical Properties:
Physical properties refer to the characteristics of a material that can be observed or measured without changing the substance's chemical composition. These properties include:

- Density: Density is the mass of a material per unit volume. It determines how tightly packed the particles of a substance are. Different materials have different densities, which can affect their behavior and applications.
- Color: Color is a visual property of a material that arises from the way it interacts with light. It is determined by the wavelengths of light that the material absorbs, reflects, or transmits.
- Hardness: Hardness measures a material's resistance to being scratched or indented. It is determined by the strength of the bonding between its atoms or molecules.
- Melting Point: The melting point is the temperature at which a solid material changes into a liquid state. It is a crucial property for processes like casting and welding, as it determines the material's behavior under heat.
- Electrical Conductivity: Electrical conductivity measures a material's ability to conduct electric current. It depends on the availability and mobility of free electrons or ions within the material.

2. Mechanical Properties:
Mechanical properties describe how a material responds to external forces or loads. They determine a material's strength, flexibility, and ability to withstand stress or deformation. Some key mechanical properties include:

- Strength: Strength refers to a material's ability to resist breaking or deforming under applied forces. It is typically measured as tensile strength, compressive strength, or flexural strength.
- Elasticity: Elasticity is a material's ability to return to its original shape after being deformed by an external force. It is characterized by properties such as Young's modulus and Poisson's ratio.
- Plasticity: Plasticity describes a material's ability to permanently deform without fracturing under applied stress. It is crucial for processes like molding and forming.
- Toughness: Toughness measures a material's ability to absorb energy before fracturing. It combines strength and ductility, indicating how well a material can withstand sudden impacts or shocks.
- Stiffness: Stiffness, also known as rigidity, refers to a material's resistance to deformation under applied forces. It is determined by the material's modulus of elasticity.

3. Thermal Properties:
Thermal properties describe a material's behavior in response to changes in temperature. They include:

- Thermal Conductivity: Thermal conductivity measures a material's ability to conduct heat. It is important for applications like insulation, cooling systems, and heat transfer.
- Thermal Expansion: Thermal expansion is the tendency of a material to expand or contract in response to temperature changes. It is crucial to consider in applications where temperature variations may cause dimensional changes or stress.
- Specific Heat Capacity: Specific heat capacity is the amount of heat energy required to raise the temperature of a material by a certain amount. It determines how well a material can store or release heat.
- Melting Point: The melting point, as mentioned earlier, is the temperature at which a solid material changes into a