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Monday, 29 June 2015

METALS AND NON – METALS

                                                  METALS AND NON – METALS
Elements are classified broadly into two categories on the basis of properties:
Metals: Iron, Zinc, Copper, Aluminium etc.
Non – metals: Chlorine, Nitrogen, Hydrogen, Oxygen, Sulphur etc.
Apart from metals and non-metals some elements show properties of both metals and non –
metals,
e.g. Silicon, Arsenic, Germanium .They are called metalloids.
Comparison of physical and chemical properties of metals and non – metals:-

Property Metals Non-Metals
1 Physical State
                                Metals are solid at room temperature. Except mercury and gallium.
Non-metals generally exist as solids and gases, except Bromine.

2 Melting and boiling points
                               Metals generally have high m.pt and b.pt except gallium and cesium. 
Non-metals have low m.pt and b.pt  except diamond and graphite. 

3 Density 
                             Generally high. 
 Generally low.

4 Malleability and Ductility
                          Malleable and ductile
. Neither malleable nor ductile.

5 Electrical and thermal conductivity
                           Good conductors of heat and electricity.
Generally poor conductors of heat and electricity except graphite. 

6 Luster
                            Poses shining luster. 
Do not have luster except iodine.

7 Sonorous sound
                            Give sonorous sound when struck.
Does not give sonorous sound.
8    Hardness     
                     Generally hard except Na, K Solid 
     non-metals are generally soft  except diamond.
Comparison of Chemical Properties of Metals and Non-metals:-
1 Reaction with Oxygen
Metal + Oxygen Metal oxide
4Na(s) + O2(g)  2Na2O(s)
4Al(s) + 3O2(g)  2Al2O3
Metals form basic oxides Zn and Al form amphoteric oxides (they show the properties of both acidic and basic oxides) Most of the metal oxides are insoluble in water Some of them dissolve to form Alkali Na2O(s) + H2O(l)  2NaOH(aq)
Non-metal + Oxygen  Non-metal oxide
 C +O2  CO2
S + O2  SO2
Non-metals form acidic oxides CO and H2O are neutral oxides(they are neither acidic nor basic in
nature) Non-metal oxides are soluble in water
They dissolve in water to form acids SO2 + H2O  H2SO3
2 Reaction with water
Metals react with water to form metal oxides or metal hydroxide and H2 gas is released. 
2Na(s) +2H2O(l)  2NaOH + H2(g) + heat
Non-metals do not react with water, steam to evolve hydrogen gas.
Because Non-metals cannot give electrons to hydrogen in water so that it can be released as H2 gas.
3 Reaction with dilute Acids
Metal + Acid  Metal salt + Hydrogen
2Na(s) + H2SO4  Na2SO4(aq) +H2(g) 
HNO3
Metal + HNO3  H2 gas is not
displaced.
Reason- HNO3 is strong oxidizing agent.
Non-metals do not react with acids  to release H2 gas
Reason- Non-metals cannot loose electrons and give it to Hydrogen ions of acids so that the gas is
released.
Mn + 2HNO3  Mn(NO3)2 + H2
H2 gas from HNO3
4 Reaction with salt solutions
When metals react with salt solution, more reactive metal will displace a less reactive metal from its salt solution.CuSO4(aq) + Zn(s)  ZnSO4(aq) + Cu(s)
When non-metals react with salt solution, more reactive non-metal will displace a less reactive nonmetal from its salt solution.
2NaBr(aq) + Cl2(g)  2NaCl(aq) + Br2(aq)
5 Reaction withChlorine
Metal + Chlorine  Metal Chloride
ionic bond is formed. Therefore Ionic compound is obtained.
 2Na + Cl2  2NaCl
Non-metal + Chlorine  Non-metal
Chloride covalent bond is formed. Therefore covalent compound is obtained.
H2(g) + Cl2  2HCl
6 Reaction with Hydrogen
Metals react with hydrogen to form metal hydride This reaction takes place only for most
reactive metals.
 2Na(s) + H2(g)  2NaH(s)
Non-metals react with hydrogen to form hydrides
 H2(g) + S(l)  H2S(g)
Properties of ionic compounds
1. Physical nature:solid and hard due to strong force of attraction. (generally brittle)
2. Melting point and boiling point:have high M.P and B.P, as large amount of heat
energy is required to break strong ionic attraction.
3. Solubility: soluble in water and insoluble in kerosene and pertrol.
4. Conduction of electricity:ionic compounds in solid state-----does not conduct
electricity.
Reason—Ions can not move due to rigid solid structure. Ionic compounds conduct
electricity in molten state.
Reason-- Ions can move freely since the electrostatic forces of attraction between the
oppositely charged ions are overcome due to heat.
Occurrence of metals.
It occurs in Earths crust, sea-water
Elements or compounds, occuring naturally Minerals that contain very high percentage
in the earth‘s crust of a perticular metal and these metals can be
extracted economically on a large scale.
e.g Bouxite ore → Aluminium
Haematite → Iron
Minerals Ores

SUGGESTED ACTIVITIES
1. Testing physical properties of metals
2. Metals are good conductor of heat
3. Metals are good conductor of electricity
4. Testing chemical properties of metals
5. To show properties of ionic compound
6. Investigating the conditions under which iron rusted
HOTS QUESTIONS (SOLVED / UNSOLVED)
Q.1 a) What are amphoteric oxides? Choose the amphoteric oxides from amongst the following:
Na2O, ZnO, Al2O3, CO2, H2O
b) Why is it that non metals do not displace hydrogen from dilute acid?
Ans. a) The oxides which are acidic as well as basic in nature are called amphoteric oxides. ZnO and
Al2O3are amphoteric oxides.
b) Non metals can not loose electrons so that H+ ions become hydrogen gas.
Q.2. What is anodizing? What is its use?
Ans. The process of forming thick oxide layer of aluminium oxide that makes it resistant to further
corrosion.
Q.3. What is Aqua regia? What is its use?
Ans. It is a mixture of concentrated HCl and concentrated HNO3 in the ratio 3:1. It can dissolve gold
and platinum.
Q.4. Give reason: Aluminium is highly reactive metal, but it is used to make utensils for cooking.
Q.5. Explain why (a) Iron articles are frequently painted. (b) Iron sheets are coated with Zinc layer.
Q.6 On adding dilute HCl acid to copper oxide powder, the solution formed is blue – green. Predict
the new compound formed which imparts a blue – green colour to the solution? Write its
equation.
Q.7. Name the property of metal used in the following cases- (i) Aluminium foil (ii) Meta jewellery
(iii) Cable wires (iv) Bells
Q.8. How can you prove that Zinc is more reactive than Copper?
Q.9. Draw and explain the electrolytic refining of impure Copper.
Q.10. Why is Aluminium extracted from Alumina by electrolytic reduction and not by reducing it with
Carbon?
Q.11 Write 3 points of difference between Calcination & Roasting?
Q.12 Write 5 points of difference between Ionic compound and covalent compound.
Q.13 What is thermit reaction? Give its one use.
Q.14 What is amalgam?
Q. 15 Magnesium when reacts with hot water, starts floating. Why?



Chemistry for class 10....
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carbon-and-its-compound-notes
periodic-classification-of-elements
unsaturated-hydrocarbon
metal-and-non-metals-notes
chemical-reaction-and-equations-notes-2
periodic-classification-of-elements


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