Chemical Bonding And Reactions
Chemical Reactions
Chemical Reaction is the reaction
in which two or more than two substances react to form a new substance is known
as Chemical Reaction. The substances which react may be ion or compound
of element.
Reaction:
Reactant reacts with each other to give product.
Reactant --------> Product
Example of general chemical reactions
from daily life is rusting of iron, formation of curd from milk etc.
Chemical Formula
Chemical Formula
is simple representation of any compound by writing together the numbers and
symbols of constituting elements forming that compound.
Example: H2O, CaCl2,
AlCl3, Ca(OH)2
Chemical Formula for Ionic Compounds
As
we know Ionic compound formed as a result of electron transfer between metal
and non-metal atoms. When we have to write chemical formula for ionic compound
then write metal atom symbol on left hand side and non-metal atom symbol on
right hand side. Metal atom name remain same but ‘ide’ or ‘ate’suffix is added
to non-metal atom name.
Ionic compound formed by one metal atom and non-metal atoms.
Metal Atom
|
Non-Metal Atom
|
Name of Compound
|
Chemical Formula of Compound
|
||
Name and Symbol
|
No.
|
Name and Symbol
|
No.
|
||
Calcium (Ca)
|
1
|
Oxygen (O)
|
1
|
Calcium Oxide
|
CaO
|
Magnesium (Mg)
|
1
|
Chlorine (Cl)
|
2
|
Magnesium Chloride
|
MgCl2
|
Aluminium (Al)
|
1
|
Chlorine (Cl)
|
3
|
Aluminium Chloride
|
AlCl3
|
Chemical Formula for Covalent Compounds
As
we know covalent compound formed as a result of electron sharing and contains
non-metal atoms. When we have to write chemical formula for covalent compound
then relatively less electronegative non-metal atom symbol is written on left
hand side and other witch is more electronegative is written on right hand side. Name of non-metal atom
which is written on left hand side is remain same but ‘ide’ suffix is added to
non-metal atom name which is written on right hand side.
Covalent compound formed by two non-metal atoms.
Low Electronegative
Non-Metal Atom
|
High Electronegative
Non-Metal Atom
|
Chemical Name of
Compound
|
Chemical Formula of Compound
|
||
Name and Symbol
|
No.
|
Name and Symbol
|
No.
|
||
Carbon (C)
|
1
|
Oxygen (O)
|
1
|
Carbon Mono Oxide
|
CO
|
Carbon (C)
|
1
|
Oxygen (O)
|
2
|
Carbon Di Oxide
|
CO2
|
Phosphorus (P)
|
1
|
Chlorine (Cl)
|
3
|
Phosphorus Tri Chloride
|
PCl3
|
Phosphorus
(P)
|
1
|
Chlorine (Cl)
|
5
|
Phosphorus Penta Chloride
|
PCl5
|
Nitrogen
(N)
|
2
|
Oxygen (O)
|
5
|
Nitrogen Penta Oxide
|
N2O5
|
Formation of Compound
We
get chemical formula of molecule by writing valence of 1st atom in
front of 2nd atom and valence of 2nd atom in front of 1st
atom.
Example: valence of carbon is 4 and oxygen is 2, write
4 in front of O and 2 in front of C in subscripts as shown below.
C2O4
as we see, both valences are multiple of two so
divide it by two to get CO2 formula.
Similarly,
Na+
+ CO3-2 ---> Na2CO3
Al+3
+ SO4-2 --->
Al2(SO4)3
Mg+2
+ N-3 --->
Mg3N2
Simple Chemical Reaction
Chemical reaction is represented by chemical
equation in brief by taking help of symbol and formula of participating
substances in reaction.
General Rule for writing Simple Chemical Reaction
1. Reactant
are written on left hand side and if more than one reactant are present than
write plus (+) sign between them.
2. Product
are written on left hand side and if more than one product are present than
write plus (+) sign between them.
3. Arrow
sign is placed between reactants and products.
Example: Zn + H2SO4
( Reactants) ----->
ZnSO4 + H2 (Products)
4. To
get more information from the reaction write temperature, pressure, catalyst
name above or below arrow sign.
sign and on
the left side of heavy substances which precipitate 
sign is placed.
6. Reactions
which absorb heat are known as endothermic reactions and (+Q)
heat sign is added on reactant side.
7. Reactions
which produce heat are known as exothermic reactions and (+Q)
heat sign is added on product side.
8. (Aq)
is written for aqueous solution substances.
Balancing of Chemical Reactions
For balancing of chemical reaction the no.
of atom on reactant side should be equal to no. of atom on product side, so
that total mass of reactant is equal to total mass of product. You read these 9
class notes at www.ChemistryNotesInfo.com
of ‘Chemistry Notes Info’ organization website.
H2 + O2 ----->
H2O (Imbalance Equation)
2H2 + O2 ----->
2H2O (Balance Equation)
Types of Chemical Reaction
· Addition Reaction
· Decomposition Reaction
· Substitution Reaction
· Oxidation and Reduction Reaction
1. Addition Reaction
Reactions in which two or more than two substances
reacts together to produce a new compound is known as Addition Reaction.
Example:-
2Mg
+ O2 ------>
2MgO
2. Decomposition Reaction
Reactions in which one compound get break into two
or more than two simple compounds by breaking of chemical bonds, these chemical
bonds get broken by heat, light or electricity.
Example:-
CaCO3
------> CaO + CO2
3. Substitution Reaction
Reactions in which one element replaces another
element to form a new compound is known as Substitution Reaction
Example:-
CuSO4
(Aq) + Zn (s) -----> ZnSO4 (Aq) + Cu (s)
4. Oxidation and Reduction Reaction
Oxidation and reduction reaction are described below
on these two basis-
Oxidation and Reduction Reaction
based on oxygen and hydrogen-
· Removal of hydrogen and addition of
oxygen is known as oxidation reaction.
· Removal of oxygen and addition of hydrogen
is known as reduction reaction.
Oxidation and Reduction Reaction
based on electron transfer-
·
Oxidation reactions are the reactions in
which atom or ion looses electrons.
· Reduction reactions are the reactions in
which atom or ion gains electrons.
Oxidation
and Reduction reactions occurs simultaneously because electron removed from one
atom or radical is added to another atom or radical.
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