Bonding Intermolecular forces 1

Kinds of molecules 2

Proof for existence of intermolecular forces 3

Types of Intermolecular forces 4

Examples to explain Van der waals’ forces 5

Examples to explain dipole-dipole forces 6

Hydrogen bonding Hδ+— Fδ- ---------------Hδ+— Fδ- hydrogen bond Considerably stronger than other intermolecular forces. Affects the physical properties of the compounds in which it exists. 7

Examples of H-Bonding 8

Hydrogen Bonding in diff. compounds 9

Examples of H-Bonding contd…. 10

Examples of H-Bonding contd…. 11

Trends in Boiling points of Groups 4,5,6 and 7 12

Examples of H-Bonding contd…. 13

Anomalous behavior of Water 14

Structure of ICE 15

Hydrogen Bonds in Water, Ice 16

Compare H2O and H2S Properties Water Hydrogen sulphide Molar enthalpy of fusion 6.0 kJmol-1 2.4 kJmol-1 Molar enthalpy of vaporization 41.0 kJmol-1 19.0 kJmol-1 State at room temperature & Pressure Liquid Gas Electro negativity Very high Less Size O atom is small S is larger than O Hydrogen Bonding 2 H bonds per molecule of water No H Bonding 17

Effect of H bonding on Organic compounds- case 1 18

Dimer of Ethanoic acid 19

Effect of H bonding on Organic compounds- case 2 Propanone is miscible in water but it has no H bonding between propanone molecules This is because its O atoms can bond to water molecules. 20

Effect of H bonding on Organic compounds- case 3 p- nitro phenol or 4- nitro phenol is having intermolecular H bonds , stronger forces of interaction between molecules and so its BP is 279°C o- nitro phenol or 2- nitro phenol has intramolecular H bonds, weaker forces of interaction between molecules and so has lower BP of 216°C 21

Biological importance of H bonding DNA pairing occurs due to H bonds. Secondary structure of proteins (α helix and β pleated proteins) α helix-is an example of INTRA MOLECULAR H Bonding 22

Hydrogen bonds in DNA Base Pairs 2 H bonds between Adenine and Thymine 3 H bonds between Cytosine and Guanine 23