How Are Materials Classified by Their Properties?
What is Material?
Material is the matter, an object is made up of. It is a relatively broad term to be defined. They are classified based upon their properties. They have properties like hardness, strength, stiffness, thermal conductivity, heat capacity, permeability, and magnetism, etc. Materials are the basic matter used in industry to be processed and purified to give other materials or objects to be used. The science dealing with the study of material is called materials science. Materials have a wide range of use. So, they are also classified based upon their use in industries. The process of determining materials to be used for an application is called material selection.
To Understand What is Meant By Material Properties
In Chemistry, knowing the properties is very important for scientists if they aim to understand what is a material, how it reacts with the other common materials around us.
Materials have a wide range of properties. However, scientifically the physical and chemical properties of matter are considered.
Physical properties may further be classified into electric, magnetic, thermal, and mechanical properties.
Chemical properties of material include their states i.e. solid, liquid, gaseous, solubility, pH, reactivity, surface tension, surface energy, corrosion, etc.
Mechanical properties of materials include their elasticity, plasticity, ductility, durability, brittleness, hardness, malleability, resilience, stiffness, viscosity, etc.
Some of the key properties of materials that are considered for a given application are given below.
Elasticity: The material tends to return to its original size and shape when the force is removed. Plasticity is the phenomenon opposite to elasticity where the material holds the new shape.
Conductivity: Thermal conductivity is the amount of heat flowing through a material.
Density: It is described by the mass of the material per cubic centimetre.
Ductility/malleability: The ability of a material to change shape when stretched without deforming is ductility or malleability.
Materials and Their Classification Bases on Properties
Based on the various properties of materials can be classified into several categories. Materials based upon atomic structure and chemical properties can be divided into metals, ceramics, and polymers.
Metals: This group of materials is composed of metallic elements like gold, iron, copper, nickel, and aluminium, etc. These materials are stiff, strong, and mostly elastic. Metals like gold and silver are ductile yet fracture resistant.
Ceramics: This group of material has metallic and non-metallic compounds, mostly oxides, nitrides, and carbides. They are relatively stiff and strong but also brittle and susceptible to fracture.
Polymers: They include plastic and rubber materials. Some common polymers are polyethylene, polyvinyl chloride, and nylon, etc. They are not as stiff or as strong as the metals or ceramics. They have low densities. They are very ductile i.e. easily made into different shapes. This is also a limitation of polymers since they are pliable they decompose or soften in a harsh environment or higher temperature.
Composites: When the above two materials are composed together, the material is called a composite. Most of these are man-made, only a few are naturally occurring. An example of a composite is fibreglass which is stiff, strong, and ductile.
Semiconductors: These materials have properties intermediate between the conductors and insulators. Some semiconducting crystals are Silicon and Germanium.
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What is Meant By Raw Material?
The material that is unprocessed or little processed and is used to make vast quantities of products is raw material. It is the basic form in which material is available naturally. These materials are further utilized by industries to produce finished products and goods. These materials are divided into direct and indirect materials. Direct materials are the raw materials used in the final product. Indirect materials are used in production but are not in the final product. Examples of raw materials are crude oil, iron ore, air, water, mineral, coal, cotton, raw biomass, etc. Metallic raw materials include tin, copper, bauxite, iron ore, lead, etc.
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FAQs on Materials in Chemistry: Definition, Classification & Examples
1. What exactly is a material in the context of chemistry?
In chemistry, a material is any substance or mixture of substances that constitutes an object. Materials can be either pure elements, like iron, or compounds, like water. They are the physical matter from which things are made, whether they are found in nature, such as wood and cotton, or created synthetically, like plastic and nylon.
2. What are the four main types of materials used in engineering and science?
The four primary classifications of materials are:
- Metals: These are known for their strength, ductility, and high electrical and thermal conductivity. Examples include iron, copper, and aluminium.
- Polymers: These consist of long molecular chains, making them lightweight and often flexible. Examples include plastics like Polyvinyl Chloride (PVC) and natural polymers like rubber.
- Ceramics: These are inorganic, non-metallic materials that are hard, brittle, and excellent insulators. Examples include glass, cement, and porcelain.
- Composites: These are created by combining two or more different materials to achieve properties that are superior to those of the individual components. A common example is carbon fibre reinforced polymer (CFRP).
3. What is the main difference between natural and synthetic materials?
The primary difference lies in their origin. Natural materials are sourced directly from nature with minimal processing. Examples include wood, stone, wool, and silk. In contrast, synthetic materials are man-made through chemical processes and do not occur naturally. Examples include polyester, nylon, and plastic, which are all derived from petroleum through polymerisation.
4. Why is it important to understand the properties of a material?
Understanding a material's properties is crucial because these properties dictate its function and application. For example, the electrical conductivity of copper makes it ideal for wiring, while the strength and corrosion resistance of stainless steel make it suitable for surgical instruments and cutlery. Knowing properties like melting point, density, hardness, and chemical reactivity allows us to select the right material for a specific job, ensuring safety, efficiency, and durability.
5. What are some common objects made from iron, copper, and plastic?
These materials are used to make a wide variety of everyday objects:
- Iron: Used primarily as steel for construction beams, vehicle frames, tools, and kitchen appliances.
- Copper: Valued for its conductivity and is used in electrical wires, plumbing pipes, coins, and cookware.
- Plastic: A versatile synthetic material used for packaging (bottles, bags), electronic casings, PVC pipes, and fabrics like polyester.
6. How do the physical and chemical properties of a material determine its specific use?
A material's application is a direct result of its unique properties. Physical properties like malleability (the ability to be hammered into sheets) and ductility (the ability to be drawn into wires) are why gold and copper are used for jewellery and wiring, respectively. Chemical properties like reactivity determine a material's stability. For instance, gold's low reactivity makes it resistant to tarnishing, preserving its value, while the high reactivity of sodium requires it to be stored in oil.
7. What is the difference between hardness and toughness in a material?
Though often confused, hardness and toughness describe different abilities. Hardness is a material's ability to resist surface scratching and indentation; diamond is an example of an extremely hard material. Toughness, on the other hand, is a material's ability to absorb energy and deform without fracturing or breaking. Steel is a very tough material. A material can be very hard but not tough, like glass, which scratches with difficulty but shatters easily.
8. How are advanced materials like composites created, and why are they so useful?
Composites are engineered by physically combining two or more distinct materials, known as constituent materials, which remain separate at a macroscopic level within the final structure. For example, fibreglass is made by embedding glass fibres (for strength) within a polymer matrix (to hold it together). Their usefulness comes from this combination, which creates a new material with a set of properties that cannot be achieved by any single material alone, such as being simultaneously strong and lightweight.
9. Why are metals typically good conductors of electricity while polymers are insulators?
The difference lies in their atomic structure and electron arrangement. Metals possess a 'sea' of delocalised electrons that are not bound to any single atom and are free to move throughout the metallic structure. When a voltage is applied, these free-moving electrons carry charge, resulting in electrical conductivity. In polymers, electrons are tightly held in strong covalent bonds between atoms and are not free to move, which prevents the flow of electricity, making them effective insulators.
