2. WHAT IS CHEMICAL BOND?
Chemical bond is defined as a
force of attraction between
atoms that holds them together
in a substance.
Why do atoms form chemical
bond?
Atoms achieve stability by
attaining nearest noble gas
configuration i.e. ns2, np6 .
2 or 8 electrons in the valence
shell of an atom is sign of
stability for atoms.
3. WHAT IS OCTET AND DUPLET RULE ?
Octet rule
Attaining of 8 electrons in the valence shell of an
atom is called octet rule.
Duplet rule
Attaining of two electrons in the valence shell of an
atom is called duplet rule.
Elements like hydrogen and helium follow duplet
rule.
4. HOW DO ATOMS FOLLOW OCTET RULE?
An atom can accommodate 8 electrons in its
valence shell in three ways.
By giving valence shell electrons (if they are less
than three) to other atom.
By gaining valence shell electron (if the valence
shell has 5 or more than 5 electrons)
By sharing valence shell electrons.
5. TYPES OF CHEMICAL BOND
Chemical bonds are of four types:
Ionic bond
Covalent bond
Dative or coordinate covalent bond
Metallic bond
6. BONDING AND NON BONDING ELECTRONS
Bonding electrons:
The valence electrons which are involve in
chemical bonding are termed as bonding electrons.
Non bonding electron:
The electrons that belongs to valence shell of an
atom but do not involve in boding is called non
bonding electrons.
7N= 1s2, 2s2,2p3
7. IONIC BOND
The type of chemical bond,
which is formed due to
complete transfer of electron
from one atom to another atom
is called ionic bond
The elements of group 1 and 2
have tendency to lose electron
while group 15 to 17 have
tendency to gain electron.
9. PROPERTIES OF IONIC COMPOUNDS
Ionic compounds are solid in nature because they
are made up of positive and negative charges .
Theses charges held together with strong
electrostatic force of attraction.
They have high melting and boiling point
They are good conductor of heat and electricity in
molten or solution form
They are mostly crystalline solid
They are easily soluble in water.
10. COVALENT BOND
The type of bond, which is
formed due to mutual sharing
of electrons is called covalent
bond.
Covalent bond form between
atoms of group 13 to group 17.
12. TYPES OF COVALENT BOND
Depending upon number of bond pair covalent
bond divided in to three types.
Single covalent bond
Double covalent bond
Triple covalent bond
13. SINGLE COVALENT BOND
When one electron is contributed by each bonded atom
is called single covalent bond.
Single covalent bond is indicated by a line (-) between
bonded atoms.
For example HCl, Cl2, CH4
14. DOUBLE COVALENT BOND
When each bonded atom contributes two electrons, two
bond pair are shared and a double covalent bonds
formed
The bond pairs are indicated as double line (=) between
atoms
For example O2, C2H4
15. TRIPLE COVALENT BOND
When each bonded atom contributes three electrons, three
bond pair are shared and a triple covalent bond formed.
The bond pairs are indicated as three line (≡) between
atoms.
For example N2 and C2H2.
16. PROPERTIES OF COVALENT COMPOUNDS
They have usually low melting and boiling point. But
large molecules with three dimensional pattern are
stable and hard so they have high melting and
boiling point.
They are bad conductors of heat and electricity but
compounds having polar character show
conductance when dissolve in polar solvent.
They are insoluble in water but soluble in non
aqueous solution like benzene, ether etc.
17. POLAR COVALENT BOND
Covalent bond is form
between different type of
atoms ( Hetero-atoms)
The bond pair of electron
will not be attracted equally.
There is a difference of
electronegativity between
two covalently bonded
atoms.
For example HCl, H2O,HF
18. NON POLAR COVALENT BOND
Covalent bond is form
between same type of
atoms ( Homo-atoms)
The bond pair of
electron will be
attracted equally.
For example:
H2 and Cl2
19. DIFFERENTIATE BETWEEN POLAR AND NON
POLAR COMPOUNDS
Polar compounds
dissolve in water.
They are good
conductor of heat and
electricity when
dissolve in polar
compounds
Non polar compounds
do not dissolve in
water.
They are bad
conductors of heat and
electricity
Polar compounds Non polar compounds