This document defines chemical reactions and describes the main types: combination, decomposition, displacement, and double displacement. It provides examples of each type of reaction and explains that a chemical reaction is represented by a chemical equation showing the reactants and products. The document also discusses exothermic and endothermic reactions, neutralization reactions between acids and bases, and the different properties of metallic, non-metallic, basic, acidic, amphoteric, and neutral oxides in chemical reactions.

1. Chemical Reactions
Any chemical change in matter
which involves transformation
into one or more substances with
entirely different properties is
called a chemical reaction.
A chemical reaction is
represented by a
chemical equation.
Substance(s)
taking part –
Reactant(s)
New substance(s)
obtained –
Product(s)
❑ Combination Reaction (or Synthesis)
❑ Decomposition Reaction
❑ Displacement Reaction
❑ Double Displacement Reaction
E.g.:-
Fe(s) + S(s) → FeS(s)
NH3(g) + HCl(g) → NH4Cl(g)
A + B + .. → C + D + ..
Types of Chemical Reactions
Two substances combine to
form a single substance
Combination Reaction
(or Synthesis)
A + B → AB
E.g.:-
2Hgo(s) → 2Hg + O2
2AgCl → 2Ag + Cl2
Decomposition reaction
One substance breaks
down into two or
more simple ones
E.g.:-
Zn + CuSO4(aq) → ZnSO4(aq) + Cu
2Na + 2H2O → 2NaOH + H2
AB + C → CB + A
C displaces
A from its
molecule.
Displacement Reaction
Double Displacement
Reaction
AB + CD → CB + AD
E.g.:-
AgNO3(aq) + HCl → AgCl + HNO3
CuO + HNO3→ Cu(NO3)2 + H2O
Two compounds in their
aqueous state displace
ions or radicals.

2. A chemical reaction in which a base or
alkali reacts with an acid to produce
salt and water.
▪ Exothermic Reaction
▪ Endothermic Reaction
A Chemical reaction in
which heat is released.
A Chemical reaction in
which heat is absorbed.
Oxides
Metallic
Oxides
Non-
Metallic
Oxides
Amphoteric Oxides: Oxides
which are of dual nature and
react with both bases and acids
to produce salt and water. Eg.
Zinc, Lead, Aluminium Oxide.
Non-Metallic
Oxides
Neutralization Reaction
Acid + Base/Alkali → Salt + Water
Metal Reactivity Series
Types of reactions based on energy exchange
Basic Oxides : Most of the
metallic-oxides are basic in
nature and react with acids
to produce salt and water.
Eg. Sodium, Calcium,
Magnesium Oxide.
➢ Formed on heating metals
➢ Some are formed on heating
metallic, cabonates, nitrates, etc.
Metallic Oxides
Acidic Oxides : Most of the
non-metallic oxides are acidic
in nature and react with bases
to produce salt and water. Eg.
Carbon, Sulphur dioxide,
Phosphorus Pentoxide.
➢ Formed on heating non-metals
Neutral Oxides : Oxides which are
neutral in nature and do not
change the colour of indicators. Eg.
Water, nitric, nitrous oxide.