SCIENCE X

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
:-

S.No

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 HO2O 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

HCl
Mg(s) + 2HCl(aq)→ MgCl2(aq) + H2(g)
H2SO4
2Na(s) + H2SO2→ 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) + n(s)→ ZnSO4(aq) + Cu(s)
When non-metals react
with salt solution, more reactive non-metal will displace a less reactive non-metal from its salt solution.
2NaBr(aq) + Cl2(g)→ 2NaCl(aq) + Br2(aq)

5

Reaction with Chlorine 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

metal properties

Minerals

Elements or compounds, occuring naturally in the earth‘s crust

Ores

Minerals that contain very high percentage of a perticular metal and these met als can be extracted economically on a large scale.
e.g Bouxite ore → Aluminium
Haematite   → Iron

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