1. Hydrogen bonding

6. hydrogen bond
Formation of hydrogen bonds between HF molecules.
Electrostatic attraction exists between partial positive charge of H atom and the lone pair electrons of F atom of another HF.

7. hydrogen bond
Formation of hydrogen bonds between H2O molecules.
Electrostatic attraction exists between partial positive charge of H atom and the lone pair electrons of O atom of another H2O.

8. hydrogen bond
Formation of hydrogen bonds between NH3 molecules.
Electrostatic attraction exists between partial positive charge of H atom and the lone pair electrons of N atom of another NH3.

10. Structure and bonding of ice
The oxygen atom of each water molecule forms hydrogen bonds with two hydrogen atoms of nearby water molecules.
a water
molecule
hydrogen
bond
hydrogen
bond
hydrogen atom
oxygen atom

11. The central oxygen atom of each water molecule has a tetrahedral arrangement of two lone pairs (forming hydrogen bonds) and two bond pairs. 1 4 2
A water molecule can
form hydrogen bonds with four other water molecules. 3

13. open structure collapses
In this open structure, water molecules are further apart than they are in liquid water.
ice
liquid water
melts
open structure collapses
water molecules tend to pack more closely together
Think about

17. Molecular size of hydride molecules increases down a group
 the VDW forces between molecules increases down a group

18. V

19. Besides van der Waal’s forces, there are hydrogen bonds between H2O molecules.
However, In H2S, H2Se, H2Te , there are weak van der Waal’s forces between molecules only.
Hydrogen bond is stronger than van der Waal’s forces
A lot more energy is needed to break hydrogen bonds between molecules
 The melting and boiling pt of water are much higher than expected.

20. Effects of intermolecular hydrogen bonding
Association
Higher melting and boiling points.
Solubility
Effects of intermolecular hydrogen bonding

21. Association: the molecule connected by intermolecular hydrogen bond associated with one another to form bigger units each of which contain two more units.
Example :

22. Fig. 28.4 The structure of ice. hydrogen bond empty space
(ball)
hydrogen bond
empty space
a water molecule

23. Higher boiling points
Increase intermolecular force of attraction requires to separate molecules, leads to higher melting and boiling point
Example:
The hydrogen atom of an ethanol molecule can form a hydrogen bond with the oxygen atom of another ethanol molecule.
High boiling point

24. Ethanol CH3CH2OH
Solubility: intermolecular hydrogen bonding b/w solute and solvent leads to higher solubility.
hydrogen bond
The hydrogen atom of an ethanol molecule can form a hydrogen bond with the oxygen atom of another water molecule.
The hydrogen atom of an ethanol molecule can form a hydrogen bond with the oxygen atom of another ethanol molecule.
High Solubility in water