CH-4 Materials: Metals & Non metals
1. Define Matter?
- Anything that occupies space and has mass is called Matter.
- Ex: chair, car, train etc.
2. Define Element?
- Element is a substance that cannot be split up into two or more simpler substances by chemical methods that is applying heat, light, electric energy.
- Ex: Iron, Oxygen , Magnesium etc.
3.How are Elements classified?
- Elements are classified into Metals, Non Metals, Metalloids.
- Metals = Metals are hard and Shiny in appearance Ex: Iron, copper, tin, gold etc.
- Non metals = Non metals are not so hard, they are mostly dull appearance. Ex: Sulphur, Phosphorus, Hydrogen, Oxygen, Nitrogen, Carbon etc.
- Metalloids – Some elements have certain properties of metals and certain properties of nonmetals. These are known as Metalloids. Ex: Arsenic, Antimony, Germanium etc.
4. Define Ores?
- Earth’s crust is the main source of Metals and Non metals.
- Minerals from which metals extracted conveniently and profitably are called as Ores.
5.What is Gangue ?
In Ores, there are certain impurities present along with metallic minerals. These impurities are called as Gangue.
6.Define Metallury ?
The series of processes carried out to extract pure metals from their ores is called Metallurgy.
Ex: Some Important Ores are
- Bauxite – A1203. H20
- Iron pyrites = FeS2
- Haematite = Fe2O3.2H2O
- Copper glance = CUS
7. Occurrence:
i) Metals = It exist both in combined State and free state.
- Combined state = Iron copper.
- Free state = Gold, platinum etc
- Na, K, ca = found in sea water
ii) Non Metals – It exist both in combined state and free state.
- Combined state – Oxides, Carbonates, Phosphates.
- Free State – oxygen in atmosphere.
- Oxygen is present in combined State in water.
Physical properties of Metals and Non Metals:
1. Physical State:
- Metals = Metals exist as solid at room temperature Ex: Gold, aluminium.
- Metals exist as liquid. Ex. Mercury
- No metals exist in gaseous state.
- Non metals: Non metals exist as Solid or gaseous.
- Ex: Solid = Sulphur, phosphorous, carbon
- Gas – H2, O2, N2 are gases.
- Bromine is the only non metal that exist as liquid at room temperature.
2. Malleability & Brittleness.
Property that allows the metals to be Hammered into thin sheets or foils is called Malleability
Metals – Metals are Malleable. Ex: Gold, Silver, aluminium, copper.
Ex: Aluminium foils are used for safe packing of foodstuff, medicine, chocolates etc.
Non metals – Non metals are non Malleable, they cannot be breaken into pieces, they are broke down into pieces.
Brittleness – Property due to non metals break up into pieces on hammering is called Brittleness.
Non metals are generally brittle
Ex: Sulphur, coal break up into small pieces on hammering.
3. Ductility:
- The property that allows the metals to be drawn into thin wires is called Ductility.
- Ex: Gold, Silver, Copper, aluminium, iron etc.
- Non metals are not ductile.
- Ex: When Stretched non metals like Sulphur, Phosphorus break into pieces and do not form wires.
4. Lustre:
Metals:
Metals are lustrous that is they have shiny surface. It makes them good reflectors of light. Ex: Gold, Silver, platinum. They are used for making Jewellery decorative articles.
Non Metals:
Non metals show dull appearance. Some Non metal iodine, graphite show some lustre.
5. Conductivity of Heat:
- Metals – They are good conductors of heat. Ex: silver, copper, iron, aluminium. They are used for making utensils, water broilers etc.
- Non metals are poor conductor of heat. Ex: Diamond is a only non metal that is a good conductor of heat.
6. Hardness:
- Metals – Metals are hard. Ex: Iron metal is hard and strong. Iron metal is used in construction of bridges, railway station etc.
- Sodium, potassium are Soft metals that can be easily cut into knife.
- Non metals are not hard or strong. Diamond is the ONLY hardest naturally occuring substance
7. Tensile Strength:
The property that allows a substance to bear lot of strain without breaking is called Tensile strength.
Metals have high tensile strength. Ex: Iron, but zinc has low tensile strength.
Non metals have low tensile strength, so they break easily, Carbon has high tensile strength
8. Density:
- Metals = Metals have high density but Na, k has low density.
- Non metals – Non metals have low density and soft but diamond has high density.
9.Conductors of electricity:
- Metals – They are good conductors of electricity. Ex: copper, aluminium, silver.
- Non metals – They are poor conductors of electricity
- Ex: Sulphur, phosphorous. Graphite is a non metal that is good conductor of electricity.
10. Sonority:
- The property of producing ringing sound by metal when it strikes with hard material is called Sonority.
- Metals are Sonorous.
- Non metals are Non Sonorous.
11. Melting and Boiling point:
Metals = They have high melting and boiling point.
Ex: Iron has a melting point 1535°C. However, Na, K, Hg, Gallium have low melting point.
Non metals have low melting and boiling point
Ex: Melting point of sulphur is 115°C. However, Diamond has very high melting point.
Chemical properties of Metals and Non metals:
Reaction with 02:
Metals react with 02 to form metal oxides that are basic.
- Mgo + H₂0 ———> Mg (OH)2
(Magnesium Hydroxide)
- 4 Na + 02 ——–>2 Na2O
- 2Zn + 02 ——–> 2Zn0
2. Non metals act with 02 to form acidic oxides
- S+ 02 ——-> S02 Sulphur dioxide
- S02 +H20 ——–> H2S03 (sulphurous acid)
- C + O2 ——-> CO2
- CO2 + H20 ———> H₂C03 (carbonic acid)
- 2N2 + 02 ——-> 2N2O (Nitrous oxide)
Exception: Metals like gold is unreactive, It does not react with air, water vapour, other gas in atmosphere so gold ornaments look “New” after years.
2. React with water:
Metals
Metals react with water and displace H₂ from water to form metal hydroxide ,
metal oxide, H₂ gas. Some metals react with cold water, some with hot water
1. 2K +2H20 ——–> 2KOH + H₂ () + Heat
cold
water
2. Mg + H2O ——–> Mgo + H2
(Boiling water/steam) Magnesium
oxide Gas
3. Zn + H₂0 ——-> ZnO +H2
Zinc
Oxide
Non Metals:
- Non metals do not react with water/steam.
- Copper, gold, silver, platinum do not react with water.
- They are used to make decorative items, coin, ornaments, Platinum is used to make alloys, electronic gadgets.
3. Reaction with acids:
Metals react with acids to form Salt and H₂ gas.
1. Zn +H2SO4 ——–> ZnSO4 + H2
2. Mg + H2S04 ——–> MgS04 + H2
Dilute HCl.
1. Mg + 2HCl ——–> MgCl2 + H2
2. 2Al +6HCl ———> 2AlCl3 + 3H2
Aluminium
Chloride
3. Fe + 2HCl ——-> FeCl₂+ H₂
4. Cu + HCl ——-> No reaction.
Non metals do not react with dilute HCl ( Ex: Coal, Sulphur)
Reaction with Bases:
Metals react with bases to form respective salt and form H₂ gas.
2Al +2NaOH + 2H2O —–> 2NaAl02 + 3H2
Sodium
aluminate
Reaction of bases with Non metals is slightly complicated.
Displacement reactions:
It is the chemical reaction in which more reactive element displaces less reactive element from its compound (salt solution)
Ex: Fe + CuSO4 ——> FeSO4 + Cu
Grey Blue Green Reddish
Brown
CUSO4 + Zn ——-> ZnSO4 + Cu
Blue Colourless Reddish Brown
CuSO4 + Mg ——-> MgS04 + Cu
Blue Colourless Reddish
Brown
FeSO4 + Zn ——–> ZnSO4 + Cu
Green Colourless Reddish
Brown
Non metals: Most of the Non metals do not show displacement reactions. But more reactive Non metals displace less reactive ones.
Ex:
2KBr + Cl₂ ——-> 2KCl + Br₂
Potassium Potassium
Bromide Chloride
Uses of Metals:
- Copper is used for making electrical wires, cables, since it is good conductor of electricity. It is used to make alloys, utensils, car radiators.
- Iron = Pig Iron is hard and brittle used to make pipe, storage tank, sink.
- Wrought Iron is tough malleable used to make belt, chain, nail, agricultural tools.
- Stainless steel (alloy of Iron) used to make utensils, Knives.
- Aluminium used to make utensils, paint, body parts of aircraft.
- Gold, Silver, Platinum used to make Jewellery, decorative items. Platinum used to make electrolytic cells
- Lead used to make electrodes for automobile batteries.
- Chrominum used for electroplating.
- Zinc used in dry cells, galvanisation (coating Iron particles to prevent rust)
Uses of Non Metals:
- Carbon is used in the form of graphite is used to make pencil lead, lubricants,. electrodes in dry cells etc.
- Carbon in form of diamond used to make Jewellery. It is used for cutting and grinding.
- Sulphur is used to make skin ointment, manufacture of dyes, gunpowder, firework, H2S04. It is also used as fungicide, insecticide.
- Iodine is used to prepare salt.
- 02 for respiration and combustion.
- Phosphorus for phosphate fertiliser, phosphoric acid and rat poison.
- Nitrogen is used for Manufacturing NH4, HNO3, fertiliser.
- Chlorine is used for disinfecting water, manufacture of bleaching powder, PVC, plastics, pipes
- Hydrogen is used in extraction of metals such as Copper, lead , tin and
- also used to manufacture ammonia gas.
Define Corrosion?
The process in which metal is reacted by the action of air, moisture or chemical on their surface is called Corrosion.
Ex: Iron, copper, silver.
How Iron objects / Define Rusting of Iron?
when Iron object is left for a considerable
time in a place where there is high moisture, it result in the formation of reddish brown flaky substance on called Rusting of Iron.
Iron + O2 + H20 ——-> Hydrated Iron Oxide
Reddish Brown. This is called Rust.
How Copper reacts with Moisture?
When copper is left for a long time in a moisture place it reacts with CO2 & H20 to form green coating of Copper hydroxide and Copper carbonate. It loses its Shine.
2Cu+ O2 + H2O + CO2 ——-> Cu(OH)2 + CuCO3
How Silver objects react with moisture ?
When silver objects are kept in air, they get tarnished and turns black. Silver reacts with H₂s in air to form a thin silver sulphide on its surface.
How to prevent Corrosion?
- Oil, grease or paint is applied on the the metal away from grease air & moisture.
- Zoating on Zinc on the surface of Iron object. This is called galvanisation.
- A layer of another metal deposited on surface of metal object by electroplating.
- Uniform protective layer of aluminium oxide is formed on aluminium object by process of anodising.
- Some other metals/ Non metals are mixed with metal objects to create alloys.
Alloy
A homogenous mixture of two or more metals along with non metals
is known as alloy.
Characteristics of alloys.
- Alloys are hard.
- They are resistant to corrosion.
- They have high tensile strength.
- Some have low melting point.
Uses of alloys.
- Carbon added to Iron increases its hardness. It is used to construct ship, bridge, vehicles.
- Stainless steel – Iron, chrominum, nickel combination is Stainless Steel. It is used to make surgical instrument, cutlery.
- Chrome steel – Combination of Iron & chrominium used to make axle, cutting tools.
- Solder – Alloy made by combining tin and lead. It is used for joining electrical wires.
- Brass combination of Copper and Zinc. It is malleable and resistant to corrosion. It is used to make utensils, screw, bolt
- Bronze- combination of copper and tin. very strong highly resistant to corrosion. used to make Statues, medals, coins.
- Duralumin – combination of Al, Cu, Mg, Mn, strong resistant to corrosion. It is used to make parts of automobiles, pressure cooker. It is light and ductile.
- German Silver – Combination of Cu, Zn, Ni, Resistant to corrosion and shines like Silver. It is used to make resistance wires and electroplating.
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