I. Classification of Materials

• Materials can be classified based on their properties, such as electrical, magnetic, thermal, mechanical, or optical properties.

• Broadly, materials are divided into three main groups: metals, polymers and ceramics.

II. Metals

• Metals are typically hard, have good thermal and electrical conductivity, and are malleable and ductile.

• They're generally characterised by their lustrous appearance, though not all of them are shiny.

• Metals can be further subdivided into ferrous (containing iron) and non-ferrous metals.

III. Polymers

• Polymers are large molecules made up of repeating subunits called monomers.

• They have a wide range of properties and can be flexible like plastic bags or rigid like Perspex.

• Polymers are typically used for their insulating and chemical resistance properties.

IV. Ceramics

• Ceramics are hard, brittle, heat and corrosion resistant materials.

• They're generally poor conductors of electricity and heat.

• Ceramics, such as glass and clay products, are often used in applications where hardness, wear resistance, or insulation is needed.

V. Composite Materials

• Composite materials combine two or more materials to meet specific engineering requirements not met by individual materials.

• The properties of composite materials are a combination of the properties of the constituent materials.

• An example of a composite material is fibreglass, which is made of fine glass fibres combined with a plastic.

VI. Smart Materials

• Smart materials respond to changes in their environment (like temperature changes) with a substantial change in their properties.

• This includes shape memory alloys, piezoelectric materials, and photochromic materials.

VII. Nano-scale Materials

• Nano-scale materials have particle sizes in the nanometre range.

• These materials possess unique physical and chemical properties due to their size.

• Such materials are used in a variety of applications in medicine, electronics, and materials science.