METALS & NON METALS

METALS AND NON METALS

F. ANSWER THE FOLLOWING QUESTIONS IN DETAIL.

1. Compare the physical properties of metals and non-metals.

s.no.	metals	Non-metals
1.	Metals are good conductors of heat and electricity	They are not good conductors of heat and electricity
2.	They are hard, shiny, can be beaten into sheets, drawn into wires	They are brittle, dull, cannot beaten into sheets, drawn into wires
3.	Normally they are solids at room temperature	They exist as solid and gases at room temperature.
4.	They are very strong and hard	Not as hard as metals.
5.	They produce sound	They do not produce ringing sound.

2. Why is gold used for making jewellery?

Gold has lustreand  is considered to be the most malleable metal. i.e. it can be beaten into thin sheets (malleability) to create a number of designs in bangles, chains etc.

3.  Why are electrical cables made from copper?

Because it is a good conductor of heat and electricity.

4. Metal oxides are basic oxides. Explain with an example.

When metal oxides dissolve in water, they form bases which turn red litmus blue. E.g.

           Sodium oxide dissolve in water to form sodium hydroxide.

         Sodium oxide + water                   sodium hydroxide

      Na₂O    +   H₂O --àNaOH

5.    Why is sodium metal stored under kerosene?

Sodium is one of the most reactive metal. It reacts vigorously with the oxygen present in air at room temperature to form sodium oxide. So, it is kept in kerosene.

6       & 7. Define displacement reaction with the help of an example.

Write the chemical reaction involved.

A chemical reaction in which a more reactive metal displaces a less reactive metal from its salt solution is called as displacement reaction.

e.g. when an iron nail is put in copper sulphate solution, the colour of the solution changes from blue to light green and a reddish brown coating of copper is seen on the iron nail.

It is because iron which is a more reactive metal displaces a less reactive metal copper from copper sulphate solution.

     Copper sulphate + iron --à iron sulphate + copper

             CuSO₄     + Fe   à   FeSO_{4    +}      Cu

8. What happens when a metal reacts with dilute acid? Explain with an e.g.

  Metals react with dilute acids form a salt and hydrogen gas.

 Sodium   + dil. Hydrochloric acid àsodium chloride +   Hydrogen

2Na  + 2 HClà 2NaCl  + H₂

9. Why do copper vessels develop a greenish layer when exposed to moist air?

Copper vessels develop a greenish coating of copper carbonate on exposure to air.

10. list few uses of metals and non metals.

p.no. 46 & 47

EXTRA QUESTIONS:

1.     a.Metals that are in liquid state: Mercury & Gallium

b.Soft metals :Sodium & Potassium

c.Non-metal that exists as a liquid :Bromine

d.Hardest non metal: diamond

e.Non- metals that have lustre: Graphite, diamond & iodine

f.      Metals which do not conduct heat & electricity: Lead &Tungsten

g.    Non-metal that is a good conductor of heat & electricity : graphite

h.    Metal used in thermometer: Mercury

2.    What is metal reactivity series?

  The arrangement of metals according to their reactivity is called as metal reactivity series.

Metals have been arranged in a vertical order with the most reactive metal at the top and the least reactive metal at the bottom.

3.    What do you mean by galvanization? What is its use?

Coating of iron or steel with a layer of Zinc is known as galvanization. It is used to prevent the metal from rusting.

4.    What is rusting? Mention the factors that cause rusting?

The formation of reddish brown coat on iron objects on exposure to moist air is known as rusting. Atmospheric Oxygen and moisture are the two factors that cause rusting.

5.    What is an alloy?

Alloy is the mixture of 2 or more than 2 metals

Or

Metal and a non-metal

e.g. brass is a mixture of copper & zinc