NCERT Gist: Materials: Metals and Non-Metals | Additional Study Material for UPSC PDF Download

- The property of metals by which they can be beaten into thin sheets is called malleability. This is a characteristic property of metals.
- The property of metal by which it can be drawn into wires is called ductility.
- Since metals produce ringing sounds, they are said to be sonorous.
- The materials other than metals are not sonorous. Materials are hard, lustrous, malleable, ductile, sonorous and good conductors of heat and electricity.
- The materials which generally posses these properties are called metals.
- The examples of metals are iron, copper, aluminium, calcium, magnesium, etc.
- In contrast, materials like coal and sulphur are soft and dull in appearance.
- They break down into powdery mass on tapping with hammer.
- They are not sonorous and are poor conductors of heat and electricity. These materials are called non-metals.
- The examples of non-metals are sulphur, carbon, oxygen, phosphorus, etc.
- Metals like sodium and potassium are soft and can be cut with a knife.
- Mercury is the only metal which is found in liquid state at room temperature. These are exceptions.
- When a copper vessel is exposed to moist air for long, it acquires a dull green coating.
- The green material is a mixture of copper hydroxide (Cu(OH) 2 ) and copper carbonate
- The ash obtained on burning magnesium ribbon is dissolved in water and tested for its acidic / basic nature. When sulphur dioxide is dissolved in water sulphurous acid is formed.
- The sulphurous acid turns blue litmus paper red. Generally, oxides of non-metals are acidic in nature. Sodium metal is very reactive.
- It reacts vigorously with oxygen and water.
- A lot of heat is generated in the reaction.
- It is, therefore, stored in kerosene. Non-metals do not react with water though  they may be very reactive in air. Such non-metals are stored in water.
- For example, phosphorus is a very reactive non-metal.
- It catches fire if exposed to air.
- To prevent the contact of phosphorus with atmospheric oxygen, it is stored in water. Non-metals generally do not react with acids but metals react with acids and produce hydrogen gas that bums with a ‘pop’ sound.
- Copper does not react with dilute hydrochloric acid even on heating but it reacts with sulphuric acid.
- The ‘pop’ sound indicates the presence of hydrogen gas.
- Metals react with sodium hydroxide to produce hydrogen gas. Reactions of non-metals with bases are complex.