Properties of Materials Unit 4 – Materials Technologies 1st ESO – IES Poeta Julián Andúgar Antonio Ruiz Hernández

Material Properties How can we choose what material should we use? Physical Properties Chemical Properties Ecological Properties

Physical Properties How they react to external stimuli? Electrical Thermal Acoustic Magnetic Optical Mechanical Other properties

Electrical Properties We can distinguish between: Electrical conductivity: metals. Electrical insulation: plastic, wood, stone, ceramics

Thermal Properties How do materials behave when heated? Thermal conductors: metals Thermal insulators: wood and plastic Fusibility: Metals, some plastics and glass. Welding: Metals, e.g. Tin.

Thermal Properties

Thermal Properties

Thermal Properties

Acoustic Properties Can you hear sound through a material? Acoustic conductors. Acoustic insulators: glass, cork & plastics

Magnetic Properties Does a magnet attract the material? Magnetism: Ferrous metals (steel).

Optical Properties Can you see light through a material? Opaque: Light don’t pass. Wood & Metals. Translucent: Light passes, but we cannot see objects behind them clearly. Some types of glass and plastic. Transparent: We can see perfectly through them: Glass and some plastics.

Optical Properties Opaque Transparent Translucent

Mechanical Properties Mechanical Strength. How the material resists the action of forces. Elasticity. The material returns to its original form after a force that has changed its shape is removed. Plasticity. The material is permanently deformed after a force is applied. Malleability: Allows a material to be spread into sheets or films. Ductility: Allows a material to be formed into filaments or wires

Other Physical Properties Density. Relation between mass of an object and its volume. Permeability: Allows water or other liquids to filter through them. Impermeability: Doesn’t allow water or other liquids to filter through them.

Chemical Properties When the chemical composition of a material changes because it interacts with other substances. Oxidation. The material reacts with the oxygen in the air or water. This happens with metals, producing rust.

Ecological Properties Recyclable materials. They can be reused (Glass, paper, cardboard, metal, plastics). Toxic materials. Harmful and sometimes poisonous (Mercury, heavy metals, petroleum). Biodegradable materials. They decompose naturally and don’t damage the environment (paper, bioplastics,…)

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