Materials – GCSE Chemistry (Triple) CCEA Revision

Characteristics of Materials

Materials are substances or things from which something is or can be made.
They cover a wide range of substances, including metals, ceramics, polymers, composites and biomaterials.
Every material has specific properties, like hardness, ductility, malleability, thermal and electrical conductivity, which determine their applications and uses.

Metals are characterised by their shiny lustre, high density, high melting points and good conduction of heat and electricity.
Metals are usually hard, ductile and malleable, which means they can be drawn into wires or beaten into sheets without breaking.
They are prone to corrosion, which is the damage caused by oxidation reactions with oxygen in the air, or by other chemical reactions.
Examples include iron, copper, aluminium, and gold amongst others.

Polymers are large molecules made up of repeating subunits, known as monomers.
Polymers can be either natural, like proteins and cellulose, or synthetic, like plastics and rubber.
They have a wide range of properties, include flexibility, resilience, resistance to chemicals and electrical insulation.
Despite their many uses, polymers, particularly plastics, can be environmentally harmful if not disposed of correctly.

Ceramics are non-metallic, inorganic solids.
Ceramics have high melting points, high hardness, and good electrical and thermal insulation.
On the downside, ceramics are often brittle, which means they can crack or break easily under stress.
Examples include pottery, bricks, glass, cement and porcelain.

Composite materials are made up of two or more distinct materials, which combined, create a new material with different properties.
Composites are designed to have the strengths of the constituent materials, and to minimise their weaknesses.
An example of a composite material is fibreglass, which is made from a plastic matrix reinforced with glass fibres.
Composites are used widely in various industries including in the production of sports equipment, automotive parts, and aircraft structures.

Biomaterials are often used in medical applications to replace or repair body tissues.
They can be derived from nature or synthesized in the laboratory.
Biomaterials must be compatible with the body and not react adversely with biological tissues and systems.
Examples include biopolymers like collagen used for wound dressing, dental implants made of ceramic, joint replacements using metallic alloys, and biomedical devices using composite materials.

Material properties can be measured and tested through various methods such as tensile testing, hardness testing and phase analysis.
Hardness testing measures the resistance of a material to deformation, indentation or scratching.
Tensile testing measures the reaction of a material to a force applied in a manner which would elongate the material.
Tests can inform material selection for specific uses or applications.

The production, usage and disposal of materials can greatly impact the environment.
Metals are typically mined, with the process often leading to habitat destruction and water pollution.
Plastics, a type of polymer, are not readily biodegradable and can take many years to break down, leading to plastic pollution.
Ceramic production involves high temperature treatments which can result in significant energy consumption.
Careful selection of materials and sustainability considerations in design and manufacturing processes can help to minimise environmental damage.