Materials: Metals and Non-metals Class 8 Science Chapter 4

Materials: Metals and Non-metals

* Lustre-
   Lustre is physical property of substance by
   which it looks shiny.

* Malleability-
   Malleability is property of metal, by which
   they can be beaten into thin sheets.

* Ductility-
   Property of metal, by which they can be
   drawn into wires, is called ductility.

* Good conductor of heat/electricity
   -The materials through which heat/electricity
   can pass, is called good conductor of
   heat/electricity.
   -Example- Iron.

* Poor conductor of heat/electricity
   -The materials through which heat/electricity
     cannot pass, is called poor conductor of
     heat/electricity.
   - Example- Plastic

* Sonorous-
   Metals are sonorous since they produce
   ringing sound.

* Physical properties of metals and Non-
   metals
   - Metals are lustrous. Non-metals are
     non-lustrous.
   - Metals are hard. Non-metals are soft.
   - Metals are solid. Non-metals are liquid or
     gas.
   - Metals are malleable. Non-metals are
     non-malleable.
  - Metals are ductile. Non-metals are
    non-ductile.
  - Metals are good conductor of heat and
    electricity. Non-metals are poor conductor of
    heat and electricity.
   - Metals are sonorous. Non-metals are
     non-sonorous.

* Chemical properties of metals and non-metals:
   - Metal + Oxygen ----> Metallic oxide
     Non-metal + Oxygen ----> Non-metallic oxide
   - Generally Metallic oxides are basic in
     nature.
     Generally non-metallic oxides are acidic in
      nature.
   - Metal + Water ----> Metallic hydroxide
     Non-metal + Water ----> Non-metallic
                                                  hydroxide
   - Metal + Acid ----> Salt + Hydrogen
   Generally non-metals do not react with acids.
   - Metal + Base ----> Salt + Hydrogen
     Non-metal + Base ----> Complex reaction
   - More reactive metal can displace less
      reactive metal from its salt.
     No such thing happens in non-metals

* Rusting of iron
Iron + Water(moisture) + Oxygen ----> Iron
                                                               Oxide(Rust)

* Corrosion of Copper
Copper + Carbon dioxide + Water + Oxygen ----> Copper Hydroxide + Copper Carbonate
 (Green)

* Sodium and Potassium are stored in
   kerosene. Because
   - Sodium and potassium react vigorously
     with air and water.
   - Sodium + Air or water ----> Reaction
     Potassium + Air or water----> Reaction

* Phosphorus is stored in water. Because it
   catches fire if exposed to air.
   Phosphorus + Air ----> Catch fire.

* Reactivity series among zinc, copper and
   iron:
       Zinc > Iron > Copper

* Displacement reaction-
   The reaction where more reactive metal
   displaces less reactive metal from its salt, is
   called displacement reaction.
 
   Example-
Copper sulphate + Zinc ----> Zinc sulphate + Copper

* Uses of metals-
   metalsare used in making machinery, automobiles, aeroplanes, trains,satellites, industrial gadgets, cooking,utensils, water boilers, etc.

* Uses of non-metals-
- Non-metal inhaled during breathing - Oxygen
- Non-metals used in fertilizer- Nitrogen, Phosphorus
- Non-metal used in water purification- Chlorine
- Non-metal used in wound as antiseptic - Iodine