Covalent bond &Ionic bond
V.S.E.P.R Theory
Hybridisation
Questions
3.
Force of attractionwhich hold two or more than two species together
is know as bond.
Chemical Bonding
Reason
To attain the state of maximum
stability species have tendency
of bonding
Classification of bonds
Oo this basis of type of species
getting bonded bond can be
classify into following categories.
H — H H2O H2O Na+ Cl–
Bond
Interatomic bond
between two
atom strong bond
200-400 kJ/mol
Intermolecular
force between
molecules weak
bond 2-40 kj/mol
➢ Non-metal + Non-metal-covalent bond
➢ Non-metal + Metal – Ionic bond
➢ Metal + Metal-Metallic bond
H-Bond 1. Ion-dipole
2. Dipole-Dipole
3. Ion-Induced dipole
4. Dipole-Induced dipole
5. London force
❑ Coordination bond is type of covalent
bond
Atoms undergoes sharing of electron.
Sharing of electron leads to the
formation of covalent bond.
Valence bond theory
Formation of covalent bond explained by three theories
Covalent bond
Lewis octet theory Valence bond theory
Molecular orbital theory
As per lewis octet theory
Bonding for stability
Stability by achieving Nobel gas
configuration
Lewis octet theory
Covalent bond
Equal sharing-Covalent bond
Unequal sharing-Coordinate bond
Sharing
4.
Incomplete octet molecules
Lewis-kosselapproach
To acquire inert gas
configuration atoms loose or
gain (e–) or share
Octet Rule: Tendency of atoms
to achieve eigtht (e–) in their
outermost shell
Exceptions to
octet rule
Expanded octet molecules
Odd (e–) molecules
Shape of molecules
XeF2; XeF4 etc.
5.
Ionic or
electrovalent bond
NaCl;KCl; MgCl2
Electrovalency: Total no. of
(e–) gain or lose by non-metal
and metal to form ion bond
Electrostatic force of attraction
between metal and non-metal
Non-directional bond
No hybridization
No Isomerism
Only empirical formula
6.
Ionic Bond
Q. Highlattice Enthalpy?
(i) NaCl MgCl2 AlCl3
(ii) NaCl MgO
Energy released when two oppositively
charged ions combine to form a crystal
lattice
Conductivity
(Molten/Aquacous)
Hard crystalline; brittle
High M.P and B.P
Solubility
{in polar solvents}
1. Low I.E. of metal
2. High electron hain enthalpy of non-metal
3. High lattice Enthalpy
Conditions
7.
Lewis dot structure:
Representsthe total no. of (e–)
present in the outermost shell
Molecule with complete
octet and donor atom should
house at least one lone pair
Acceptor atom molecule it
should be electron-deficient
Coordinate bond
Example:
NH3. BF3; NH4Cl; K4 [Fe (CN)6]
Ek tarfa pyaar
8.
Formal Charge:
F.C [V – L –
𝟏
𝟐
S]
V = Total no. of valence (e–) for
atom in free state
L = Total non-bonded or lone pair
electrons
S Total no. of shared (e–)
Resonance:
Delocalization of () electrons
. . . .
:O:
||
C
:O–: :O–:
10.
Mutual sharing ofelectrons
Formation of bond is done with a
release of energy
Covalent Bond
Polar covalent bond
Non-Polar covalent bond
11.
Covalent Bond:
➢ Physicalstate: In all
F2; Cl2; Br2; I2
gas liquid solid.
➢ Conductivity: Poor
➢ Solubility: Non Polar
➢ Isomerism
➢ Directional Bonds
➢ Slow Reactions
Covalency:
➢ Total of bonds made by central
atom through sharing
➢ Total no. of half filled atomic
orbitals.
➢ Maximum covalency is
generally shown in exited
state.
➢ PCl5 exists but NCl5 doesnot.
13.
Polarization in ionicbond
Small size of cation
Large size of anion
High charge on anion or cation
FAZAN'S RULE
No Bond is 100% Ionic.
Cation: Polarising power
Anion: Polarizability
{Anion gets distorted}
Pseuto Inert gas electronic configuration
14.
Applications of Fazan'sRule:
Polyatomic ions {CO3
2–; SO4
2–; HCO3
–, NO3
–}
I. Thermal decomposition of Metal carbonates
Li2CO3
𝛥
li2O + CO2; But Na2CO3; K2CO3; and rest can't
Increasing thermal li2CO3 < Na2CO3 < K2CO3 < RbCO3 < Cs2CO3. stability
order
For metal Halides: {Small anions: F–; Cl–; O2–; OH–; S2–; N3– etc.}
We see lattice energy rather than polarization concept
LiF > LiCl > LiBr > LiI
1
Polarization Covalent character
Thermal
15.
Intensity of Colour:
AgClAgBr AgI Ag2S
White Pale yellow Dark yellow Black
Cl– < Br– < I– Large size 𝜶 Polarization 𝜶 Intensity of anion
Solubility of Ionic Compounds: {H.E. > L.E.} Soluble
Case-I: {When rc ra} {For small anions like: O2–; S2–; N3–; F–; Cl–; OH– etc.}
➢ Lattice energy is the deciding factor:
H.E. > L.E.
Solubility ()
Top (As) ()
(L.E.) ( )
Bottom H.E. ()
(i) It iskind of (Intermolecular) lewis acid-base interaction.
(ii) Partial pi bond or coordinate pi bond.
(iii) Types: (A) p – p Back bonding
(B) p – d Back bonding
(iv) Conditions: Donor atom Acceptor atoms
2nd period 2nd or 3rd period
lone pair vacant orbital
Back Bonding
26.
1. Valence bondtheory
Valence bond theory
Proposed by Heitler and London
as per VBT bonding takes place
for attaining stability.
1
Stability
Potential energy
➢ Bond formation is an
exothermic process.
➢ During this process some
extent of electron cloud merge
into each other, this part is
known as overlapped region
and this process is known as
overlapping.
➢ Only those orbitals of valence shell
can exhibit overlapping which has
➢ Unpaired electron
For example:
H-Cl bond form by overlapping of
1s-3p orbitals
H → 1s1
Cl → 1s2 2s2 2p6 3s2 3p5
➢ Opposite spin
Strength of covalent bond
Strength of covalent bond extent of
overlapping.
1. Nature of orbitals
(a) No. of shell: Lower the number of
shell higher overlapping.
Bond strength
/size of orbitals
1-1 > 1-2 > 2-2 > 2-3
➢ Exception:
Cl2 > Br2 > F2 > I2 due to lip-lp
O–O < S–S repulsion
N–N < P–P
1
No. of shell
27.
S-non-directional
P-directional
(B) Type ofsub-shell
Valence shell contain subshell s and p
Directional orbital has
higher extent of
overlapping.
Possible combination and strength of overlapping
s-s < s-p < p-p
This factor is applicable when number of shell is same
otherwise shell factor prominent 2s - 2s < 2s - 2p < 2p - 2p
sub-shell factor 1s - 1s > 1s - 2s > 1s - 3s shell factor
(a) Axial overlapping:
Along the internuclear
axis; form sigma () bond,
strong bond.
(b) Co-lateral overlapping:
Side wise overlapping has less
extent of overlapping form
-bond
➢ In case of multiple bond between two atom one bond is sigma
and rest are pi-bonds.
➢ VBT was not able to define geometry of molecule therefore a
new concept came into existence known as hybridization.
Hybridisation
➢ Intermixing of atomic orbitals and formation of new orbital these orbitals
are known as hybrid orbital and this concept is known as hybridisation.
➢ It is hypothetical concept.
➢ Only those orbitals can participate in hybridisation which has slight
difference in energy.
➢ No. of hybrid orbitals: No. of atomic orbitals participate in intermixing.
➢ Hybrid orbitals oriented at maximum possible distance three
dimensionally
➢ On the basis of type of orbitals participating in hybridization, we can
divide hybridization into following categorise.
29.
Dipole Moment
Measurement ofPolarity in a molecule
μ = q × d
debye = esu-cm
1D = 10-18 esu.cm
(A) Identification of polar or Non-polar molecule.
Molecule: Symmetrical distribution of electron cloud-
Non-polar. Molecule: Unsymmetrical distribution of
electron cloud- Polar.
Diatomic Molecule:
(a) Homoatomic ΔΕΝ = 0 → μ = 0 → Non-polar
H2, F2, Cl2, N2 etc.
(b) Heteroatomic EN ≠ 0 = 0 → μnet = 0 → polar
HF > HCI > HBr > HI
Polyatomic molecule:
R → Vector sum of bond moment
R →
Important Order:
NH3 > NF3
H2O > H2S
CH3Cl > CH3F > CH3Br > CH3I
CH3CI > CH2CI2 > CHCI3 > CCI4
μ1
2
+ μ2
2
+ 2μ1μ2cosθ
Applications:
Predict shape and polarity of molecule Symmetrical geometry → = 0 → non-
polar Unsymmetrical geometry → µ ≠ 0 → polar Distinguish between cis & trans
form
Dipole moment in Aromatic Compounds
Maleic acid
0
fumaric acid
= 0
μ ∝
1
bond angle
30.
Strength
Intermolecular H-bond >Intramolecular H-bond
➢ Intramolecular H-bonding takes place in ortho
derivatives only
Hydrogen Bonding
Electrostatic force of attraction between hydrogen & highly
electronegative atoms.
It is dipole-dipole type of attraction
Hydrogen should be covalently bonded with highly
electronegative elements. Like : F, O & N.
Strength of H-bond Electronegativity of electronegative
elements should
Type of Hydrogen Bond
Intermolecular Intramolecular
Between molecule Within molecule
➢ It is not an intermolecular
force
➢H₂O is liquid while H2S is gas.
➢HF is liquid while HCl is gas.
EXAMPLES
Applications of H-bonding
Physical State (densile nature) H-bond
Melting Point (mp) H-bond
Boiling Point (bp) H-bond
Viscosity H-bond
Surface Tension H-bond
Volatility . 1/H-bond
Vapour Pressure . 1/H-bond
31.
Molecular Orbital Theory
Givenby Hund & Mulliken given
Given To explain:
➢O2: Paramagnetic nature.
➢Existence of species like H2
+, H2
–
As per MOT bond form by combination of atomic orbitals &
interference of electron wave interference of electron wave
leads to formation of molecular orbitals.
atomic orbitals electron
waves - interference
constructive interference destructive interference
Constructive Interference
same phase wave - bonding molecular orbital (BMO)
Destructive Interference
opposite phase wave - anti-bonding molecular orbital (ABMO)
Therefore by the combination of two atomic orbitals
there is formation of two molecular orbitals; BMO &
ABMO.
➢ Energy level BMO < ABMO,
➢ All atomic orbitals of an atom participate in
combination and form molecular orbitals with
atomic orbitals of another atom.
➢ Energy level of molecular orbital 1s *1s 2s *2s
2px = 2py 2pz *2px *2py 2px
Total electron <14
Internuclear axis = z
➢ Bonding electron (N2) → No. of electrons present in BMO.
➢ Anti-bonding electron (N2) → No. of electrons present in ABMO.
➢ Bond order: No. of Bonds present between two atoms.
➢ Paramagnetic nature: If any molecule orbital contain unpaired
electron either bonding molecular orbital or anti-bonding molecular
orbital it would be paramagnetic otherwise diamagnetic.
➢ Isoelectronic species:
Same bond order - same magnetic properties.
Significant of MOT
B. O. =
N2 − N2
2
Stability of molecule B.O.
Bond strength B.O.
Bond length
1
B. O.
32.
Formation of molecularorbitals by linear
combination of atomic orbitals
Formation of bonding () and antibonding (*) molecular orbitals by the linear
combination of atomic orbitals yA and yB centred on two atoms A and B respectively.
1. Bond Order
2.Stability of O2 molecule
3. Electronic Configuration:
4. Magnetic Character
5. Magnetic Moment
41.
N2 → N2
+NO → NO+
O2 → O2
2– O2 → O2
+
In which of the following processes, the bond order has increased and paramagnetic
character has changed to diamagnetic?
QUESTION_2019
A
C
B
D
42.
Bonding Parameter
1.Bond length:Internuclear distance
Factor affecting Bond length
(i) Atomic size: bond length size [No. of shell]
(ii) EN, Bond length
1
EN
(iii) Bond order: Bond length
1
B.O
(iv) Hybridisation : Bond length
1
%age of s−character
dA−B = rA + rB − 0.09 × ΔENÅ
Bond Angle : Angle between two adjacent bond is
known as bond angle.
bonded atom
bond angle
bond angle
central atom
Factors Affecting Bond Angle
(i) Hybridisation:
Bond angle %age of s-character
(ii)No. of lp/bp:
[when hybridisation is same]
Bond angle
1
lp
Eg. : CH4 > NH3 > H2O:
(iii) Type of Central atom: Applicable when :
➢ hybridisation same
➢ No. of Ip/bp same.
Bond angle EN of central atom
Eg. NH3 > PH3 > AsH3 > SbH3
:
: