it is the notes of class 11 of electronegativity

4. ELECTRONEGATIVITY

5. DIFFERENCES BETWEEN EGE AND
ELECTRONEGATIVITY
ELECTRON GAIN ENTHALPY
1. Tendency of an isolated
gaseous atom to attract an
electron.
2. It can be measured
experimentally.
3. It is the property of an
isolated atom.
4. EGE of an atom is constant.
ELECTRONEGATIVITY
1. Tendency of an atom in a
molecule to attract shared
pair of electrons.
2. It cannot be measured
experimentally.
3. It is the property of a
bonded atom.
4. It has a relative value.

6. ELECTRONEGATIVITY VALUES

7. PAULlNG SCALE OF ELECTRONEGATIVITY
• EA-A , EB-B , EA-B = bond dissociation enthalpies of A-A ,B-B,
A-B respectively

20. M

21. In the above structure u can see there is O-H bond as well as S-
OH bond. But there is not considerable electronegativity
difference between Sulphur and oxygen. Hence this bond will
not break.but the there is considerable E.N difference between
oxygen and hydrogen atom.hence it releases H+ ion instead of
OH- ion
EN OF
O=3.5
S=2.5
H=2.1

23. APPLICATIONS OF ELECTRONEGATIVITY
METALLIC AND NON-METALLIC CHARACTER
As the electronegativity increases, non-
metallic character increases
As electronegativity decreases, metallic
character increases.

24. APPLICATIONS OF ELECTRONEGATIVITY
POLAR AND NON-POLAR BONDS

25. FACTORS ON WHICH ELECTRONEGATIVITY
DEPENDS
1. STATE OF HYBRIDIZATION
Electronegativity of carbon % s character

26. VARIATION OF ELECTRONEGATIVITY WITH
HYBRIDISATION

27. FACTORS AFFECTING ELECTRONEGATIVITY
2. OXIDATION STATE OF ELEMENT
As the oxidation state of the element
increases, electronegativity increases.
Fe3+ (1.96) has higher electronegativity
than Fe2+ (1.83).

29. FACTORS AFFECTING ELECTRONEGATIVITY
3. NATURE OF SUBSTITUENTS ATTACHED
Carbon atom in CF3I acquires greater
positive charge than in CH3I. So, carbon
atom in CF3I is more electronegative than
in CH3I.

30. ELECTRONEGATIVITY AND OXIDATION
NUMBERS

31. VALENCE ELECTRONS
• Electrons present in the outermost shell of an
atom are valence electrons
• The number of these electrons determine the
valency.

32. VALENCE ELECTRONS
ALONG A PERIOD: Increase from 1 to 8
ALONG A GROUP: Remain the same
Noble gases are zerovalent. Their valency
is zero since they are chemically inert.

33. ANOMALOUS PROPERTIES OF SECOND PERIOD
ELEMENTS
First member of a particular group of elements in the s and p
blocks shows anomalous behaviour compared to other
elements due to

37. DIAGONAL RELATIONSHIP
Some elements of second period show same
properties with elements of next period and
next group i.e. diagonally placed elements due
to same charge/radius ratio and same
polarising power.

39. CHEMICAL REACTIVITY
Chemical reactivity is high at two extreme ends and
lowest at the centre.
Chemical reactivity of alkali metals on extreme left is due
to their ability to lose an electron and form cation due to
low IE. So, alkali metals are good reducing agents.
Chemical reactivity of halogens on extreme right is due to
their ability to gain extra electrons and form anion. So,
halogens are good oxidising agents.

40. CHEMICAL REACTIVITY

41. NATURE OF OXIDES AND CHEMICAL
REACTIVITY
Chemical reactivity of an element can be best shown by
it’s reactions with oxygen and halogens.
The alkali metals readily combine with oxygen to form
basic oxides (Na2O, K2O)
The halogens readily combine with oxygen to form
acidic oxides(SO3 , Cl2O7)

42. NATURE OF OXIDES AND CHEMICAL
REACTIVITY
Oxides of elements in the centre are either
amphoteric (Al2O3 , As2O3 ) or neutral(N2O , NO , CO).
Amphoteric oxides show both basic as well as acidic
properties
Neutral oxides show neither basic nor acidic
properties.

43. INERT PAIR EFFECT
• Reluctance of two s-electrons to participate in
bonding due to poor shielding effect of d and f
electrons.
• In group 13 elements , stability of group
oxidation state +3 decreases down the group
whereas stability of +1 oxidation state 2 units
less than group oxidation state increases down
the group .
• In group 14 elements, stability of +4 decreases
down the group whereas stability of +2 increases
down the group.