1. CHEM 120 WEEK 12 LECTURES (INORGANIC WEEK 3)
Dr. MD BALA

2. Intramolecular Bonding
The bonding between molecules or atoms in the solid state
Ionic bonding e.g. sodium chloride
Covalent bonding e.g. Graphite or diamond
Metallic bonding e.g. copper/gold etc.
Van der Waals bonding e.g. iodine or benzene
Hydrogen bonding e.g. water and alcohols

3. IONIC BONDING Ions stack together in regular crystalline structures.
Typically ionic solids.
Have high melting and
boiling points
They are brittle.
They form electrolyte solutions if they dissolve in water.

4. requires more energy to break up requires less energy to break up
Ionic Solids
The attractive force between a pair of oppositely charged ions increases with increased charge on the ions and with decrease in ionic sizes
requires more energy to break up
requires less energy to break up
Na+ = 99 pm

5. COVALENT BONDING Electron sharing
Complete their octets by sharing electron pairs F
e.g. Consider F2
The electronic configuration of F is 1s22s22p5 F F
These are combined to form F2.

6. Metallic bonding
It is a special case:
The electrons are considered
to be “delocalized”
This gives rise to their
properties such as
malleability or ductility.
Good thermal and
electrical conductors

7. Electrostatic forces and the reason ionic compounds crack

8. Ionic compound dissolved in water
Electrical conductance and ion mobility
Solid ionic compound
Molten ionic compound
Ionic compound dissolved in water

9. van der Waals - Due to instantaneous dipoles
non-conducting species

10. Bond Polarity
Covalent bonding between unlike atoms results in unequal sharing of the electrons
One end has larger electron density than other
The result is bond polarity
End with larger e- density gets partial - charge
End that is e- deficient gets partial + charge
H F •  
Dipole Moment 6

11. Allotropy and Polymorphism
e.gs. of elements and their allotropes
Polymorphism:

12. Bonding in other elements and their chemistries
Sulfur

14. Rhombic and monoclinic are different allotropes of sulfur
(same elements but different structural or molecular units)

15. Phosphorous
Linear molecule with triple bond sp
hybridized

16. Compounds of oxygen (oxides)

17. Acidity increases left to right
(metalloids form amphoteric oxides)
(metals form basic ionic oxides)
(non-metals form acidic covalent oxides)

18. Acids and Bases Arrhenius definition:
An acid provides H+ ions (ionizable hydrogen) and a base produces OH- ions in an aqueous solution
Bronsted-Lowry:
An acid is a proton donor and a base is a proton acceptor
Lewis acids and bases:
- An acid is a species that is an e- pair acceptor and a base is an e- pair donor.

19. (base anhydride)
Anhydride means “without water”. A “base without water” becomes a basic solutione when it reacts with water:
CaO (s) + H2O Ca2+ (aq) + 2OH- (aq)
base oxide calcium hydroxide
The oxide ion is protonated to produce the hydroxide:
O H2O OH- (aq) (100%)
A basic oxide reacts with acids to produce water
CaO (s) + 2H+ (aq) Ca2+ (aq) + H2O (l)

20. Sulfurous acid Sulfuric acid
Oxoacids contain H and O and one other nonmetal
Sulfurous acid
Sulfuric
acid

21. base
acid
acid
base
tetra(hydroxo)aluminate(III) ion

22. Exercise
1. Write a balanced equation for Zn(OH)2 with: a) an acid b) a base 2. Does the following species act as an acid, a base or an amphoteric species? a) PO43- b) CH3NH3+ = CH3NüH2 + H+

24. Oxoacids Obtained from the dissolution of acidic oxides in water
e.g. CO2 + H2O = H2CO3(aq)

25. What are some Oxoacids?

26. What are polyprotic acids?
They are acids with more than one ionizable H atom per molecule
e.g. H3PO4 phosphoric acid (3 ionizable H atoms triprotic
H2SO4 sulfuric acid diprotic
H2SO3 sulfurous acid ’’
H2CO3 carbonic acid ’’

27. Halogens as oxoacids

28. hypo-chlorite
chlorite
chlorate
perchlorate

29. especially
E0 = V

30. the hydrogen in HOCl is attracted to the lone pair on
oxygen atom in water
water accepts a proton base
HOCl donates a proton acid
Exercise:
What is the oxidation number of Cl in HOCl?
What is the oxidation number of Cl in OCl-?
What is the oxidation number of Cl in HClO4?

31. Strengths of oxoacids
How great is the pull of electrons away from the O-H bond?
Affected by:
1. The electronegativity of the central atom
2. The no. of terminal O atoms in the acid molecule

32. Which acid is stronger, H2SO4 or H2SO3?
= 103
= 1.3 x 10-2 a1 a1

33. Exercise
Which acid is stronger?

34. Nitrogen Nitrogen has oxidation nos. from -3 to +5
The most industrially useful states are:
-3 for ammonia NH3
0 molecular nitrogen N2
+5 for nitric acid HNO3
Physical description: NO is colourless, paramagnetic (1 unpaired e-) and toxic

35. Generation of NO: Prepared by the action of Cu(II) salts on nitric acid (HNO3):
colourless

36. nitrite(III)
colourless

37. colourless