1) Metals react with oxygen to form metal oxides, with reactivity varying between metals. The most reactive metals, such as sodium and potassium, burn vigorously while copper is the least reactive. 2) Metals also react with water and acids, producing hydrogen gas and alkaline or salt solutions. More reactive metals like sodium and potassium react violently with water. 3) Displacement reactions occur when a more reactive metal is placed in a solution of a less reactive metal salt, displacing the metal from its salt.

1. CHEMICAL
Dr. Pranabjyoti Das
Arunodoi Junior College
5/6/2021 1
Pranabjyoti Das

2. Metals can be well described only on
the basis of their chemical properties.
1) Reaction of metals with oxygen
Almost all metals react with oxygen to form metal oxide, but the
reactivity differs for different metals. Metals react with oxygen to form
metal oxides. Metals donate electrons to oxygen for the formation of metal
oxides.
Metal + Oxygen  Metal oxide
4K + O2 → 2 K2O
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3. Chemical properties of Metals
Sodium is the most reactive metals. Sodium reacts
with oxygen in air at room temperature to form sodium
oxide. Hence, sodium is stored under kerosene oil to
prevent its reaction with oxygen, moisture and carbon
dioxide
4Na + O2 →2Na2O
Potassium is also a reactive metal. Like sodium,
potassium also reacts instantly with oxygen to
produce potassium oxide
4K + O2 → 2 K2O
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4. Most Metal oxides are insoluble in
water.
But some of the metal oxides
dissolve in water to form alkalis,
and they are basic in nature
Example: Sodium oxide Na2O and potassium
oxide K2O dissolve in water to produce alkalis
Na2O+H20→2NaOH
K20 + H20 →2KOH
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5. Magnesium does not react with oxygen
at room temperature.
But on heating, Magnesium, burns in air
with intense light and heat to form
magnesium oxide (MgO)
2Mg + O2 → 2MgO
Zinc burns in air on heating to form zinc oxide
2Zn + O2 →2ZnO
Iron filings burn in the flame of theburner
3Fe + 202 heat →Fe304
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6. Copper is least reactive. It does not burn, but
on heating, the hot metal is coated with a black
coloured layer of copper oxide
2Cu + O2 →2CuO
Aluminium develops a thin layer of oxide when
exposed to air
4Al + 302 →2Al2O3
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7. Amphoteric oxides
Metal oxides are usually basic in nature but some
metal oxides such as aluminium oxide (Al2O3) and
zinc oxide (ZnO) react both with acids as well as
bases to produce salt and water. Such metal
oxides are called as Amphoteric Oxides.
Al2O3 +6HCl→2AlCl3+ 3H2O
Al2O3 +2NaOH→2NaAlO2+ H20
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9. Metals like potassium and sodium react vigorously
with cold water to liberate hydrogen gas which
immediately catches fire producing a lot of heat.
(Exothermic reaction)
2K + 2H2O →2KOH+H2+ Heat
2Na+ 2H2O→2NaOH+H2+Heat
2. Reaction of Metals with Water
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10. Reaction of Na with water
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11. Calcium reacts with water less vigorously.
The heat evolved is not sufficient for hydrogen to
catch fire.
Ca + 2H2O →Ca(OH)2 + H2
Magnesium reacts with hot water to form
magnesium hydroxide Mg(OH)2 and hydrogen
hydrogen gas.
Mg + H2O →Mg(OH)2 + H2
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12. Metals like aluminium, iron and zinc do not react
either with cold or hot water but they react with
steam to form their respective metal oxide and
hydrogen gas.
2Al + 3H2O →Al2O3 + 3H2
3Fe + 4H2O →Fe3O4 + 4H2
Metals like Gold, Silver, Platinum and Copper do
not react with water at all. So they are called as
noble metals
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13. 3) Reaction of metals with acids
Metals react with acids to give salt and hydrogen
gas. Let us see the following reactions….
Mg +2HCl→MgCl2+ H 2 ↑
2Al + 6 HCl →2AlCl3+ 3H2 ↑
Zn+2HCl→ZnCl2+ H 2 ↑
Fe +2HCl→FeCl2 + H 2 ↑
The reactivity decreases in the order,
Mg > Al > Zn > Fe
Copper doesn’t react with acids as Copper is less
active than Hydrogen.
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14. Nitric acid HNO3 And Metals….
Hydrogen gas is not evolved when a metal
reacts with nitric acid, as it is a strong oxidizing
agent. It oxidizes the hydrogen to water and itself gets
reduced to any of the nitrogen oxides (N20, nitrous
oxide; NO, nitric oxide; NO2 nitrogen dioxide etc)
But magnesium and Manganese react with dilute
HNO3 to evolve hydrogen gas
Mg + 2HNO3 →Mg(NO3)2 + H2
(magnesium +nitric acid →magnesium nitrate +hydrogen)
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15. Element Reaction with Air Reaction with Water Reaction with Acid
Potassium
Sodium
Burns vigorously
to form oxides
With cold water forms
hydrogen gas and
alkaline hydroxide
solution. React with
decreasing vigour down
the series till Ca
Violent reaction to
give hydrogen gas
and salt solution
Calcium
Magnesium
Aluminium
Zinc and
Iron
Burn with
decreasing
vigour down the
series
Mg reacts with hot
water to fomi
magnesium hydroxide
and hydrogen gas. For
Al, Zn and Fe, no
reaction with cold and
hot water. With steam
forms metal oxide and
hydrogen gas
React to form
hydrogen gas and
salt solution with
decreasing vigour
down the series
Reactions of metals with air, water and acids
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16. 4. Reactions of metals with solutions of metal salts
Let us put an iron nail in a solution of copper
sulphate. The iron nail gets coated with a reddish
brown colour copper and the blue colour of copper
sulphate solution fades out. In this reaction more
reactive iron has displaced copper which is less
reactive from the copper sulphate solution
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17. This reaction is known as displacement reaction. The
brown coating on the iron nail shows that copper is
deposited on the iron nail by displacing iron
The greenish colour of the solution in the test tube
shows that Fe2+ ions are present in the solution. This
shows that iron is more reactive than copper, as Fe2+ ions
have displaced Cu2+ ions from copper sulphate solution
Fe + CuSO4 →Cu + FeSO4
MetalA+ Salt solution B→ Salt solutionA+ Metal B
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18. 5. Reaction of Metals with Non-metals
Let us look at the electronic configuration of
some metals and non-metals. It will help us to
understand the reactivity of different elements and
formation of different compounds
We have learnt that noble gases have a
completely filled valance shell, hence are chemically
inactive
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19. Electronic configuration of some metals and non-metals
Type of
element
Element Atomic
number
Electronic
configuration
K L M N
Metals Sodium (Na) l l 2 8 1
Magnesium (Mg) 12 2 8 2
Aluminium (Al) 13 2 8 3
Potassium (K) 19 2 8 8 1
Calcium (Ca) 20 2 8 8 2
Non-metals Nitrogen (N) 7 2 5
Oxygen (O) 8 2 6
Fluorine (F) 9 2 7
Phosphorus (P) 15 2 8 5
Sulphur (S) 16 2 8 6
Chlorine (Cl) l7 2 8 7
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20. Sodium is a silver coloured metal that reacts so
violently with water that flames are produced due
to formation of hydrogen gas.
On the otherhand, Chlorine is a greenish coloured
gas which is so poisonous that it was used as a
weapon in World War l
When chemically bonded together, these two
dangerous substances form a compound sodium
chloride so safe that we eat it every day (common
table salt)
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21. Sodium (2.8.1) atom has one electron in its outermost
shell. If it loses one electron from its "M" shell then its
"L" shell becomes the outermost shell to acquire a
stable octet. The nucleus of this atom still has 11
protons but the number of electrons has become 10, so
there is a net positive charge giving us Sodium cation
(Na+)
On the other hand chlorine (2, 8, 7) has 7 electrons in
its outermost shell and requires one more electron to
complete its octet
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22. Formation of Sodium Chloride (NaCl)
2.8.1 2.8.7
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23. Ionic or Electrovalent Compound
Sodium and chloride ions being oppositely charged
attract each other and by strong electrostatic forces of
attraction to exist as sodium chloride (NaCl), resulting in
the formation of an electrovalent or ionic bond compound.
Such a bond formed by the give and take of
electrons is called as ionic or electrovalent bond.
Compounds formed in this manner by the transfer of
electrons from a metal Na to a non-metal Cl are known as
ionic compounds or electrovalent compounds
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24. Properties of ionic compounds
1. Ionic compounds are solids and hard due to strong force of
attraction between positive and negative ions
2. They are generally brittle and break into pieces when
pressure is applied
3. Ionic compounds have high melting and boiling points, as a
considerable amount of energy is required to break the
strong inter molecular attraction
4. They are generally soluble in water and insoluble in
solvents such as kerosene, petrol, etc.
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25. Ionic compounds in the solid state do not
conduct electricity because the movement of
ions in the solid state is not possible due to
their rigid structure, but they conduct
electricity in the molten state. The conduction
of electricity through a solution involves the
movements of charged particles. A solution of
an ionic compound in water contains ions,
which move to the opposite electrodes when
electricity is passed through the solution
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26. Thank You
Dr. Pranabjyoti Das
Arunodoi Junior College
Tangla
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Pranabjyoti Das