The World of Metals and Non-metals

Metals are generally hard, lustrous, malleable, ductile, and good conductors of heat and electricity.

Lustre

Objects made from copper, aluminium, and iron are lustrous in appearance and are hard. Lustre shown by metals is known as metallic lustre.

Materials like copper, aluminium, and iron are known as metals, whereas, coal, sulfur, and wood are non-lustrous and not as hard as metals.

Some metals like sodium and potassium are so soft that they can be cut with a knife. There is one metal, mercury, that is found in a liquid state at room temperature.

Malleability

Objects such as a piece of copper, an iron nail, and a piece of aluminium become flat when beaten, whereas other objects or materials behave differently. The property by which materials can be beaten into thin sheets is called malleability. Most metals possess this property. For example, thin silver foil on some sweets and aluminium foil used for wrapping food items. These are formed due to their malleability. Gold and silver are the most malleable metals.

A piece of coal or a lump of sulfur does not show this behaviour. They break into pieces and are said to be brittle. On the other hand, wood neither gets flattened into a sheet nor breaks into pieces. Therefore, wood is neither malleable nor brittle.

Ductility

The property of materials by which they can be drawn into wires is called ductility. This property of ductility is mainly possessed by metals.

For example, wires of metals like copper or aluminium in electrical fittings. Some ornaments, like bangles, necklaces, earrings, etc., are also made from metal wires. Metal wires play important functions in a variety of stringed musical instruments, such as veena, sitar, violin, and guitar.

Sonority

The property of metals that enables them to produce a ringing sound is called sonority, and metals are said to be sonorous in nature.

Conduction of Heat

The transfer of heat from one point to another of a material is called conduction, and materials that transfer heat are called conductors.

Metals are good conductors of heat, whereas wood is a poor conductor of heat. For example, mostly metal vessels are used for cooking, and their handles are made with wood or other materials that do not conduct heat.

Conduction of Electricity

Materials that allow electricity to flow through them easily are called good conductors of electricity. In contrast, materials that prevent the bulb from glowing by not allowing electricity to pass through them are called poor conductors of electricity.

For example, plastic covering on screwdrivers and rubber gloves protect the electrician from electric shock because these materials are poor conductors of electricity.

Effect of Air and Water on Metals

Iron objects develop brown deposits when left in the open for a few days. Moist air is responsible for the development of brown deposits on objects made of iron. This brown deposit is called rust. The process of formation of rust on objects made of iron is called rusting. The rusting of iron can be prevented by several methods such as painting, oiling, greasing, and applying a protective layer of zinc metal on iron (galvanisation).

Many other metals also exhibit discolouration when kept open in the atmosphere. For example, formation of a green coating on the surface of copper objects or a black coating on the surface of silver objects. Gradual deterioration of metal surfaces caused by air, water, or other substances is known as corrosion.

Metal Oxides

Generally, oxides of metals are basic in nature.

For example, magnesium ribbon burns with a dazzling white flame and changes into a white powder. This powder is magnesium oxide. It is formed due to the reaction between magnesium and oxygen present in the air.

Adding a few drops of warm water to this white powder makes the solution of magnesium oxide. It changes the colour of red litmus paper to blue. Hence, it is basic in nature.

Sodium is a metal which is stored in kerosene because it reacts vigorously with oxygen and water. A lot of heat is generated in the reaction. Storing sodium in kerosene prevents its exposure to moisture and air.

Non-Metals

Substances like sulfur and phosphorus behave differently with air and water than metals. Phosphorus is stored in water as it catches fire when exposed to atmospheric air. These substances are usually soft and dull in appearance. They are neither malleable nor ductile, and they are not sonorous. They are also poor conductors of heat and electricity. These are called non-metals. Their oxides are acidic in nature.

Some other non-metals are oxygen, hydrogen, nitrogen, carbon, etc.

On burning sulfur in air (oxygen), sulfur dioxide gas is formed. On dissolving sulfur dioxide gas in water, sulfurous acid is formed.

Uses of Non Metal

We breathe in oxygen, which is a non-metal, and without it, we would not be able to survive.

Carbon is essential in everyday life because it is the building block of all life forms. It is a key component of proteins, fats, and carbohydrates, which are necessary for growth and energy.

Nitrogen is used in the manufacturing of fertilisers and other chemicals. It is an essential nutrient for the growth of plants.

Chlorine is a non-metal commonly used in water purification.

A solution of iodine, a non-metal, is applied on wounds as an antiseptic.