Materials

Why are saucepans made of metal?

Saucepans are made of metal because most metals heat up quickly. Metal atoms vibrate easily when heated, rapidly passing on the vibrations of atom around them. This makes metals good conducted (carriers) of heat. Most metals, such as iron, are strong, shiny, hard solids, but metals all have different properties. Aluminium, for example, is light and easily molded.

How is glass made?

Glass is made by heating together sand, ash, and stone in a hot furnace. The molten (liquid) glass is then rolled into sheets, put in a mould, or blown into shapes. It hardens to a transparent solid when it cools. Glass is waterproof and reflects light or let light through it. It is used to make windows and jars, and also lenses and mirrors.

What are plastics?

Plastics are artificial materials made by heating chemicals found in petroleum (oil). Plastics have many useful properties. They can be be molded into different shapes, they do not break easily when dropped, and they are light and waterproof. There are many different types of plastic. For example, Plexiglass is a tough, tranperant plastic and polystyrene is a kind of foam used for insulation (to trap heat).

When is plastic a problem?

Plastic is a problem because it does not biodegrade, or break down, as food, paper, or wood do. This means plastic piles up in large holes in the ground or floats around oceans, washing up on beaches. Scientists are developing plastics that break down but can still protect and store goods.