Materials: Metals and Non- Metals

The property of metals by which they can be beaten into thin sheets, is called malleability. Aluminium is a metal. Aluminium foils are made by using this property of aluminium. They keep food items warm and prevent them from getting contaminated.

As we know metals react with acids and produce metal salts and hydrogen gas, aluminium is a metal and lemon contains citric acid. So if we store lemon pickle in an aluminium utensil after some time utensil metal will get corroded due to reaction and lemon pickle inside will not be fit for human consumption.

The property of metals by which they can be beaten into thin sheets is called malleability. This is the characteristic property of metals which is exploited to make silver foil for decorating food items and aluminium foil to store food items. Non-metals do not show this property, on beating a coal or wood they get break down into small pieces, thus we can say that metals are malleable and non-metals are not malleable.

The property of metals by which it can be drawn into wires is called ductility, thus we can see aluminium or copper wires around us. Non-metal do not show this property so we never see plastic wires around us, they are not ductile.

This is because metals produce ringing sound and are called sonorous while non-metals do not show this property.

1. Reaction with oxygen:-
   Metals react with oxygen to form metallic oxides. These are basic oxides because they react with water to form bases. E.g. Magnesium burns in air to form magnesium oxide.Magnesium reacts with water to form magnesium hydroxide.
   2 Mg + O2 ---> 2 MgO MgO+ H2O ---> Mg(OH)2
2. Reaction with water:-
   Metals react with water to form metal hydroxides and hydrogen.
   Eg. Sodium reacts with water to form sodium hydroxide and hydrogen.
   2 Na + 2 H2O ----> 2 Na OH + H2
   Magnesium reacts with water to form magnesium hydroxide and hydrogen.
   Mg + H2O ----> Mg(OH)2+ H2
3. Reaction with acids:-
   Metals react with acids to form metallic salts and hydrogen.
   Eg. Zinc reacts with dilute hydrochloric acid to form zinc chloride and hydrogen.
   Zn + 2 HCl ----> ZnCl2+ H2
4. Metals replace metals:-
   A more reactive metal replaces a less reactive metal from its salt solution.
   Eg. Magnesium replaces copper from copper sulphate solution to form magnesium sulphate and copper.
   Mg + CuSO4 ----> MgSO4+ Cu
   Zinc replaces copper from copper sulphate solution to for zinc sulphate and copper.
   Zn + CuSO4 ----> ZnSO4 + Cu

1. Reaction with oxygen:
   Non-metals react with oxygen to form non-metallic oxides. These oxides are acidic oxides because they react with water to form acids.
   Eg. Sulphur burns in air to form sulphurdioxide. Sulphurdioxide reacts with water to form sulphurous acid.
   S + O2 ---> SO2
   SO2+ H2O ---> H2SO3
2. Reaction with water:
   Non-metals do not react with water
3. Reaction with acids:
   Most non-metals do not react with acids.
   Some non-metals like sulphur react with concentrated nitric acid to form sulphur dioxide, nitrogen dioxide and water.
   S + 4 HNO3 ---> SO2+ 4 NO2+2 H2O

The surface of some metals gets corroded when exposed to moist air for a long time. This is called corrosion. Rusting of iron is an example of corrosion, here an oxide is formed and the chemical equation for the same is;The chemical equation for rusting of iron is
2Fe + 3/2 O2 ----> Fe2O3.xH2O

When a copper vessel is exposed to moist air for long time, it acquires a dull green coloured coating on its surface; this green material is the mixture of copper hydroxide and copper carbonate. Reaction is as follow:
2Cu+H20+CO2+02 ----> Cu(OH)2 + CuCO3

1. Reaction with oxygen:
   Non-metals react with oxygen to form non-metallic oxides. These oxides are acidic oxides because they react with water to form acids.
   Eg. Sulphur burns in air to form sulphurdioxide. Sulphurdioxide reacts with water to form sulphurous acid.
   S + O2 ---> SO2
   SO2+ H2O ---> H2SO3
2. Reaction with water:
   Non-metals do not react with water
3. Reaction with acids:
   Most non-metals do not react with acids.
   Some non-metals like sulphur react with concentrated nitric acid to form sulphur dioxide, nitrogen dioxide and water.
   S + 4 HNO3 ---> SO2+ 4 NO2+2 H2O

The arrangement of metals in decreasing order of their reactivity is called reactivity series of metals. Reactivity series of metals is used to summarize information about the reactions of metals with acids and water, single displacement reactions and the extraction of metals from their ores.

Metals that retain their lustre because they do not react with air, water or acids are called noble metals. Like gold, silver, platinum etc. gold and silver are used in making jewellery, coins and medals and platinum is used for making metals are used for making jewellery, electrical gadgets, etc.

Metals plays very important role in our day to day life, metals like iron is used for making pins, nuts, nails, bolts tools, machines etc., aluminium is used for making utensils, wires, parts of aircraft, vehicle, packaging of food stuffs and medicines etc., copper is used for making wires, vessels and electrical gadgets. Gold and silver are used in making jewellery, coins and medals and platinum is used for making metals are used for making jewellery, electrical gadgets, etc. sodium compounds are used as common salt, calcium compounds are used for making cement, glass etc.

Non-metals are essential for our life. Non-metals like oxygen are used for respiration by living beings and for burning of fuels. Nitrogen is used for making ammonia which is an important constituent of fertilizers used for improving soil quality for crop production. Sulphur is used for making sulphuric acid and salts of metals. Hydrogen is used for making ammonia which is used for making fertilizers and as fuels in rockets. Chlorine is used to kill germs in water and iodine is used as an antiseptic as well as a disinfectant.

Corrosion of metals can be prevented by :

• Applying oil grease
• Applying paint
• Galvanisation
• Electroplating
• Alloying: (Eg. When iron is alloyed with chromium and nickel, it forms stainless steel which is resistant to corrosion)

Burn a magnesium ribbon in air, and analyse the ash which is formed. The ash obtained by burning magnesium ribbon is dissolved in water and tested for its acidic or basis nature, we will observe it turns red litmus blue, thus concluded oxides of magnesium is basic in nature, amd in general metallic oxides are basic in nature.

Metallurgy is the science of extraction of metals from their ores and their purification. It involves following steps:

• Concentration of the ore: is the removal of impurities from the ore.
• Reduction: the process of obtaining the metal from its compound.
• Refining: is the process of purification of the impure metals to obtain the pure metal.

When a copper vessel is exposed to moist air for long time, it acquires a dull green coloured coating on its surface;this green material is the mixture of copper hydroxide and copper carbonate. Reaction is as follow:
2Cu+H20+CO2+02 ----> Cu(OH)2 + CuCO3

1. Reaction with oxygen:
   Non-metals react with oxygen to form non-metallic oxides. These oxides are acidic oxides because they react with water to form acids.
   Eg. Sulphur burns in air to form sulphurdioxide. Sulphurdioxide reacts with water to form sulphurous acid.
   S + O2 ---> SO2
   SO2+ H2O ---> H2SO3
2. Reaction with water:
   Non-metals do not react with water
3. Reaction with acids:
   Most non-metals do not react with acids.
   Some non-metals like sulphur react with concentrated nitric acid to form sulphur dioxide, nitrogen dioxide and water.
   S + 4 HNO3 ---> SO2+ 4 NO2+2 H2O

1. Reaction with water:-
   Metals react with water to form metal hydroxides and hydrogen.
   Eg. Sodium reacts with water to form sodium hydroxide and hydrogen.
   2 Na + 2 H2O ----> 2 Na OH + H2
   Magnesium reacts with water to form magnesium hydroxide and hydrogen.
   Mg + H2O ----> Mg(OH)2+ H2
2. Reaction with water:
   Non-metals do not react with water

In a displacement reaction a more reactive metal can replace a less reactive metal, but a less reactive metal cannot replace a more reactive metal. For e.g.Iron replaces copper from copper sulphate solution to form iron sulphate and copper
Fe + CuSO4 ---- FeSO4+ Cu
Based on the reactivity of metals, they can be arranged in the decreasing order of their activity.

Physical properties of metals:

• Metals are solid except mercury.
• Metals are hard.
• Metals are malleable that is can be beaten into thin sheets.
• Metals are ductile that is can be drawn into wires.
• Metals produce ringing sounds are called sonorous.
• Metals are lustrous.
• Metals are good conductors of heat and electricity.

Physical properties of non-metals:

• Non- metals are solid, liquid or gas.
• Non- metals which is solid are brittle (diamond is the hardest).
• Non- metals are soft and dull in appearance.
• Non- metals are not malleable, and break down into powdery mass on tapping with a hammer.
• They are not sonorous.
• They are poor conductors of heat and electricity..