# Introduction to metals
# Some important metals
*Iron
*Aluminum
*Copper
*Silver
*Gold
# Position of metals (Fe, Al, Cu, Ag and Au) in periodic table, occurrence and ore, physical properties and uses.
# Occurance of metal in Nepal
Metal: It is more electropositive substance having malleable and ductile property and good conductor of heat and electricity. Metals are extracted from their ores.
Ores: Ores are the naturally occurring substances from which metals can be extracted conveniently and economically.
Metallurgy: The process of extraction metals from their corresponding ore is called metallurgy.
Iron
Symbol: Fe
Atomatic number: 26
Atomatic weight: 56
Valency: 2 or 3
Ores:
1. Haematite (Fe₂O₃)
2. Magnetite ( Fe3O4 )
3. Siderite (FeCo3 )
4. Iron pyrite
5. Limonite
Physical properties
(i) Pure iron is a shiny grey-white metal,
(ii) lt is malleable and ductile,
(iii) It is a good conductor of heat and electricity,
(iv) lts specific gravity (i.e. density) is 7.86,
(v) It has high melting point (1500°C) and boiling point (2500°C),
Uses of iron
(i) Iron is used for making rods, pipes and cables.
(ii) Iron is used to make steel, household utensils, factory equipments, weapons, etc.
(iii) Iron is used in bridges, buildings and vehicles.
(iv) Iron is used as a catalyst in the preparation of ammonia gas by Haber's process.
Aluminum
Symbol: Al
Atomatic number: 13
Atomatic weight: 26
Valency: 3
Ores
1. Bauxite (AI203.2H20)
2. Felspar [ K(AISiO3O8)]
3. Diaspore (Al2O3.H2O)
4. Clay and Slate ' (AI203.2SiO3.2H2O)
5. Cryolite (Na3AIF6)
6. Kaolin AI2Sl2O7.2H2O
Physical properties
(i) Aluminium is a bluish-white metal.
(ii) It is a light metal having density 2.7 gcm³.
(iii) It is quite malleable and ductile.
(iv) It is a very good conductor of heat and electricity.
(v) Its melting point is 660oC and boiling point is 1800oC.
(vi) It can be cast and welded.
Uses
1. Aluminium is used for making household cooking utensils.
2. Aluminium is used for making overhead electric transmission lines.
3. Aluminium foils are used for packing food items like biscuits, chocolates, medicines, cigarettes, etc.
4. Aluminium metal is used in making bodies and parts of aeroplanes, ships, cars, trucks, trains, photo frames, etc.
5. It is used for making coins, silver paints and mirrors.
Copper
Symbol: Cu
Atomatic number: 29
Atomatic weight: 63.5
Valency: 1 or 2
Ores
1. Chalcopyrite (CuFeS2)
2. Chalcocyte (Cu2S)
3. Cuprite (Cu20)
4. Azurite [Cu(OH)2]
5. Malachite [CuCO3.Cu(OH)2]
Physical properties
(i) Copper is a reddish-brown metal which is highly malleable and ductile.
(ii) lt is an extremely good conductor of heat and electricity.
(iii) It is a quite heavy metal having density 8.95 g/cm³.
(iv) lts melting point is 1083°C and boiling point is 2350°C.
(v) It readily forms alloys like brass (80% copper and 20% zinc), bronze (90% copper and 10% tin) and German silver (60% copper, 20% zinc and 20% nickel.)
Uses
(i) Copper is used for making electric wires for household electric wiring, electric motor, dynamos and other electrical appliances as it is highly ductile and one of the best conductors of electricity.
(ii) Copper is used for making cooking utensils, boilers, kettles, calorimeters, etc. as it is highly malleable and very good conductor of heat.
(iii) Copper is used for electroplating and making printed electronic circuits. (iv) Copper is used for making coins, alloys,
(v) Copper salt is used as insecticide, fungicide etc.
Silver
Symbol: Ag
Atomatic number: 47
Atomatic weight: 107.8
Valency: 1
Ores
(i) Argentite or silver glance (Ag2S)
(ii) Horn silver (AgCI)
(iii) Silver copper glance [(AgCu)2.S]
(iv) Pyrolitc or Ruby silver [3Ag2S.Sb2S3]
Physical properties
(i) It is a shiny white metal.
(ii) It is a very good conductor of heat and electricity.
(iii) Its specific gravity is .
(iv) It's melting point is 960°C and boiling point is 1955°C.
Gold
Symbol: Au
Atomatic number: 79
Atomatic weight: 197.2
Valency: 1 or 3
Ores
1. Reef gold
2. Sandy alluvial soil
3. Quartz vein
4. Calverite (AuTe2)
Physical properties
(i) Gold is a lustrous yellow coloured metal.
(ii) It is a very good conductor of heat and electricity.
(iii) It is highly malleable and ductile.
(iv) It's specific gravityis 19.3
(v) It melts at 1063°C and boils at 2530°C.
Uses
(i) It is used for making valuable jewelleries, coins, medals, etc.
(ii) It is used in gold plating.
(iii) It is used for making statues, gold leaf electroscope crown bridge and medicines.
(iv) It is also used in photography.
1. What happens when silver reacts with hot and concentrated sulphuric acid?
Ans: When silver reacts with hot and concentrated sulphuric acid, silver sulphate, sulphur dioxide and water are formed.
2. What happens when silver reacts with a concentrated nitric acid?
Ans: When silver reacts with concentrated nitric acid, silver nitrate, nitrogen dioxide and water are formed.
3. What happens when gold reacts with the solution of potassium cyanide in the presence of excess air?
Ans: When gold reacts with the solution of potassium cyanide in the presence of excess air, potassium aurocyanide and potassium hydroxide are formed.
4. What is metallurgy?
Ans: Metallurgy is the process of extracting metals from their respective ores.
5. What is crushing of the ore?
Ans: The process in which the lumps of the ores are crushed into smaller pieces with the help of crusher or hammer is called crushing of the ore.
6. What is calcination?
Ans: Calcination is a process of conversion of metallic ores containing carbonates and hydroxides to their respective oxides by heating strongly below their melting point, either in the absence of air or in a limited supply of air.
7. What is roasting?
Ans: Roasting is the process of conversion of the calcinated ore into metallic oxide by heating at a temperature below its melting point in excess of air.
8. What is aquaregia?
Ans: Aquaregia is the mixture of conc. HCl and conc. HNO3 in the ratio of 3:1.
9. What happens when silver reacts with hot and concentrated sulphuric acid?
Ans: When silver reacts with hot and concentrated sulphuric acid, silver sulphate, sulphur dioxide and water are formed.
10. What happens when silver reacts with a concentrated nitric acid?
Ans: When silver reacts with concentrated nitric acid, silver nitrate, nitrogen dioxide and water are formed.
11. What happens when copper is heated in dry air?
Ans: When copper is heated in dry air, copper is gradually converted into copper oxide and finally red cuprous oxide at a higher temperature.
12. What happens when copper reacts with concentrated hydrochloric acid?
Ans: When copper reacts with a concentrated hydrochloric acid, it forms cuprous chloride with the liberation of hydrogen gas.
13. What is a concentration of the ore?
Ans: The removal of impurities present in the powdered ore is called concentration of the ore.
14. What happens when iron is strongly heated in air?
Ans: When iron is strongly heated in air, it forms a black compound called ferroso-ferric oxide.
15. What happens when iron is exposed to moist air?
Ans: When iron is exposed to moist air, a brown scale of rust is deposited on its surface.
16. What happens when steam is passed over red hot iron?
Ans: When steam is passed over red-hot iron, ferroso-ferric oxide and hydrogen gas are formed.
17. Which gas is produced when iron reacts with a concentrated hot sulphuric acid?
Ans: When iron reacts with a concentrated hot sulphuric acid, sulphur dioxide gas is produced.
18. What are metals?
Ans: Metals are electropositive elements, which are shiny and good conductor of heat and electricity.
19. What are minerals?
Ans: Minerals are the naturally occurring substances having characteristics chemical composition.
20. What are ores?
Ans: Ores are the naturally occurring substances from which metals can be extracted conveniently and economically.