View
63
Download
0
Category
Tags:
Preview:
Citation preview
08-Dec-13 6
Sodium has 1 valence electron
Cl: 1s22s22p63s23p5Na: 1s22s22p63s1
Chlorine has 7 valence electrons An electron transferred gives
each an octet
Cl17
---
--
--
-
--
--
--
--
-
Na- -
--
-- -
--
-
-
Na+ 1s22s22p6
This transfer forms ions, each with an octet forms
Cl- 1s22s22p63s23p6
The resulting ions come together due to electrostatic attraction forming Nacl
7
Properties of Ionic Compounds
Structure: Crystalline solids
Melting point: Generally high
Boiling Point: Generally high
Electrical Conductivity:
Excellent conductors, molten and aqueous
Solubility in water:
Generally soluble
8
Covalent BondingThe bond arises from the mutual attraction of 2 nuclei
for the same electrons.
9
HB+ H
AH
BH
A
A covalent bond is a balance
of attractive and repulsive forces.
A covalent bond is formed by the overlap of orbital's of one atom ,with the orbital of another atom
1. Only an orbital with unpaired electrons is eligible for overlapping
2. For orbital to overlap, the electrons in overlapping orbital's should spin in the opposite direction
3. After overlapping the shape of orbital's change suchthat a greater electron density Appear between the nuclei of atoms along internuclear axis
Conditions for overlapping are :
10
The factor which decides the strength of covalent bond is the extent of overlap, it
depends on the shape of orbital's .The spherical ‘s’orbital’s can not overlap
efficiently, where as the extent of overlapping the dumb bell shaped
p orbital's more
11
Strength of covalent bond
Overlapping Of Orbital'ss-s overlapIt involves mutual overlap of half filled s-orbitals of the atoms
approaching to form a bond. s-p overlapIt involves mutual overlap of half filled s-orbitals of the one
atom with half filled p-orbital of the other..p-p overlapIt involves mutual overlap of half filled p-orbitals of the two
atoms.
Order of strength of overlapping : p-p > s-p > s-s 12
Sigma bond (σ)Sigma bond is formed by an axial or head-on overlapping of pure atomic orbital's It
is end to end overlap. Sigma bonds are re presented by Greek latter σExamples: (σ bond)
13
Pi bond (∏) A pi body is formed by the sidewise overlapping of pure atomic
orbital's.the extent of overlapping is less, hence a pi bond is weaker than σ bond
A bond pair means 2 electrons involved in bonding
Alone pair means a pair of 2 electrons not involved in bonding
14
••
H Cl••
••
This is a LEWIS ELECTRON DOT structure.
shared or bond pair
Unshared or
lone pair (LP)
VSEPR THEORY and MOLECULAR GEOMETRY
This theory helps in explaining the shapes of single covalentmolecules. according to this theory the Various electron pairsaround a central atom orient themselves in a such way that thereis minimum repulsion and maximumstabilityThe decreasing order of repulsions among electron pairs is asunder
Lone pair -Lone pair > Lone pair-Bond pair > Bond pair -Bond pair
15
(Valence Shell Electron Pair Repulsion)
Steric Number 1
17
StericNo.
Basic Geometry
0 lone pair 1 lone pair2 lone pairs 3 lone pairs 4 lone pairs
1linear
1 atom bonded to another atom
Steric Number 2
18
StericNo.
Basic Geometry
0 lone pair1 lone pair 2 lone pairs 3 lone pairs
2linear linear
2 atoms, or lone electron pairs, or a combination of the two, bonded to a central atom.
Steric Number 3
08-Dec-13 19
StericNo.
Basic Geometry
0 lone pair1 lone pair 2 lone pairs 3 lone pairs
3trigonal planar bent / angular linear
3 atoms, or lone electron pairs, or a combination of the two, bonded to a central atom.
Steric Number 4
20
StericNo.
Basic Geometry
0 lone pair1 lone pair
2 lone pairs 3 lone pairs
4tetrahedral
trigonalpyramid bent / angular linear
4 atoms, or lone electron pairs, or a combination of the two, bonded to a central atom.
Steric Number 5
21
StericNo.
Basic Geometry
0 lone pair 1 lone pair 2 lone pairs 3 lone pairs
5trigonal
bipyramidsawhorse /
seesaw t-shape linear
5 atoms, or lone electron pairs, or a combination of the two, bonded to a central atom.
Steric Number 6
22
StericNo.
Basic Geometry
0 lone pair 1 lone pair 2 lone pairs 3 lone pairs
6Octahedral square pyramid square planar
6 atoms, or lone electron pairs, or a combination of the two, bonded to a central atom.
Steric Number 7
23
StericNo.
Basic Geometry
0 lone pair 1 lone pair 2 lone pairs 3 lone pairs
7pentagonal bipyramidal
pentagonal pyramidal
7 atoms, or lone electron pairs, or a combination of the two, bonded to a central atom.
Recommended