ALL ABOUT METALS. SKG Tutorials - Class 8

Size: px
Start display at page:

Download "ALL ABOUT METALS. SKG Tutorials - Class 8"

Transcription

1 ALL ABOUT METALS SKG Tutorials - Class 8

2 Metals 2 Elements can be classified as metals and non-metals. Metals are strong and durable. Thus metals are used so widely for making almost everything. Example: Metals are used in making machinery, automobiles, aeroplanes, buildings, trains, satellites, gadgets, cooking utensils, water boilers...etc. However not all metals are hard, strong and durable solids. Sodium and potassium are soft metals which can be cut with a knife. Mercury is a liquid metal.

3 Physical Properties of Metals 3 Physical properties are those which we perceive with our senses. Metals are hard. (Except lithium, potassium and sodium.) Metals are solids. (Except mercury) Metals are very good conductors of heat and electricity. (Silver and copper) Metals are ductile : can be easily shaped into wires. Metals are malleable ( they bend without breaking) : can be easily shaped into thin flat sheets. Metals are sonorous: make a sound when struck with hard objects. Metals are lustrous :can be polished to a shiny appearance. High melting and boiling point. (Exception: Gallium and caesium can melt in your palm ) High tensile strength: handle max. stress Cooking utensils, irons, heaters, etc. are all made of metals

4 An Experiement 4

5 Chemical Properties of Metals 5 Chemical properties describe how one substance reacts with others. Rust formation: Iron reacts with atmospheric oxygen and moisture to form iron oxide, which is commonly known as rust. Articles made of iron, such as grills, fencing, etc. are get rusted because of reaction with moist air.

6 Chemical Properties of Metals 6 Reaction with oxygen: Metals burn in the presence of oxygen to form metal oxides. These metal oxides are basic in nature. 2MgO Magnesium Oxide Mg(OH) 2 Magnesium Hydroxide

7 Chemical Properties of Metals 7 Reaction with water: Sodium in water Sodium in air

8 Chemical Properties of Metals 8 Reaction with Acids: Metals react with acids and produces hydrogen gas. Copper Sulphate Powder Copper Sulphate Solution

9 Chemical Properties of Metals 9 Reaction with Bases: Only few metals can react with strong bases to metal salts and releases hydrogen gas. Sodium zincate solution

10 Chemical Properties of Metals 10 Metals replace metals:- A more reactive metal replaces a less reactive metal from its salt solution.

11 Activity series of metals 11 The arranging of metals in the decreasing order of their reactivity is called activity series of metals. In decreasing order of reactivity:

12 Noble metals 12 Metals like gold, silver, platinum etc. retain their lustre because they do not react with air, water or acids. So they are called noble metals.

13 Uses of metals 13 Iron :-is used for making pins, nails, nuts, bolts, tools, machines, construction of buildings, bridges etc. Aluminium :-is used for making utensils, wires, furniture, parts of aircrafts, vehicles, machines, for packing food and medicines etc. Copper :- Gold :- Silver :- Platinum :- Sodium :-. Calcium :-.

14 Practice Exercises Which metal is found in liquid state at room temperature? 2. What is the product when sulphur reacts with oxygen? 3. Which metal can be cut with knife? 4. Name the metal used in thermometer.? 5. What is the colour of CuSO4 and ZnSO4? 6. What happens when sulphur dioxide dissolves in water? 7. Why sodium is stored in kerosene? 8. Which metals are used for making ornaments? 9. The sulphuric acid turns blue litmus paper into which colour? 10. Which metal is found in plants? 11. Metallic oxides are acidic or basic in nature? 12. Which metal is used for decorating sweets? 13. What happens when metal react with bases? 14. Why Handle of screw driver and is not made up of metal?

15 15 Please ask questions for better understanding To know more please mail us.