1. Chemical Bonds

2. Sodium Chloride

3. Chemical Bonds
Transfer of
electrons
Formed by
Sharing of
electrons
Ionic bondsIonic bonds Covalent bondsCovalent bonds
Atoms are
joined
together
COMPOUND

4. Ionic Bonds
 Formed through transfer of electrons between
atoms of metal and non-metal.
 Example of metals:
 sodium, magnesium, iron, lead, aluminium
 Example of non-metals:
 Chlorine, sulphur, oxygen
 Metal atoms donate electrons
 Non-metals atom accept electrons
Achieve
stablestable
electronelectron
arrangementarrangement
Achieve
stablestable
electronelectron
arrangementarrangement

5. Ionic Bonds
Neutral
atom
Donates
electrons
Cation
(+)
Accept
electrons
anion
(-)

6. Formation of Ionic Bonds
 Ionic compounds
 Formed through ionic bonds
 Example 1: sodium chloride
 Sodium atom: electron arrangement : 2.8.1
 Chlorine atom : electron arrangement : 2.8.7

7. Formation of ionic bonds of in
sodium chloride
Na Cl
Na Cl

8. Formation of ionic bonds in
sodium chloride
 Electron arrangement of sodium atom is 2.8.1
 A sodium atom donates one electron to achieve the stable octet
electron arrangement (2.8)
 Sodium ion, Na+
is formed
 This electron is transferred to a chlorine atom with an electron
arrangement of 2.8.7
 A chlorine atom accepts electron from sodium atom to achieve the
stable octet electron arrangement (2.8.8)
 Chloride ion, Cl-
is formed
 The sodium ion and chloride ion, formed are attracted to one
another to form a solid sodium chloride,
 The strong electrostatic force between the ions is called ionic bond
(electrovalent bond)

9. Formation of Ionic Bonds
 Example 2: magnesium fluoride
Mg
F
F
MgF F

10. Formation of ionic compound magnesium fluoride
 Electron arrangement of magnesium atom is 2.8.2
 A magnesium atom donates two electron to achieve the stable
octet electron arrangement (2.8)
 Magnesium ion, Mg2+
is formed
 This electron is transferred to two fluorine atom with an electron
arrangement of 2.7
 two fluorine atom accepts 1 electrons each from magnesium atom
to achieve the stable octet electron arrangement (2.8)
 Fluoride ion, F-
is formed
 The magnesium ion and fluoride ions, formed are attracted to one
another to form a solid magnesium floride, MgF2.
 The strong electrostatic force between the ions is called ionic bond
(electrovalent bond)

11. Covalent Bonds
non-metal atoms
Share electrons
Stable electron
arrangement
Single bond
Double
bond
Triple
bond
a pair of electrons
is shared
two pairs of
electrons are
shared
three pairs of
electrons are
shared
Formed by

12. Single Bond
 Formed when a pair of electrons is shared between 2 atoms.
 Example : hydrogen molecule
 Hydrogen atom has 1 valence electron
 Needs 1 more to achieve duplet electron arrangement
 2 hydrogen atoms contribute one electron each for sharing
 This shared pair of electrons forms a single bond in hydrogen
molecule, H2

13. Lewis Dot Structure
G. N. Lewis 1875-1946

14. Double Bond
 2 pair of electron are sharing between atoms
 Example: formation of an oxygen molecule, O2
 An oxygen atom has 6 valence electron
 Needs 2 electron to achieve octet electron arrangement
 2 oxygen atom each contribute 2 electrons for sharing
 A double bond is formed between 2 atoms

15. Triple Bond
 Is formed when 3 pairs of electron are shared between 2 atoms
 Example: formation of a nitrogen molecule, N2
 Nitrogen atom has the electron arrangement of 2.5.
 It needs 3 more electron to achieve stable electron arrangement.
 Each atom contribute 3 electron each
 Thus sharing 3 pairs of electrons
 Triple bond is formed between the nitrogen atoms.

16. Comparison between the ionic bond
and covalent bond
Ionic bond
 Metal atoms
and non-metal
atom
 Transferring
electron
 Positively
charged ion
and negatively
charged ion
Covalent bond
 Non metals
atoms
 Sharing
electrons
 molecules
Types of
Elements involved
in the formation
of each bond
How each bond
is formed
The particles in
the compound
formed

17. Try this out!
Draw the electron arrangement of the formation
for the following ionic compounds:
[Proton number : Li, 3 ; Na, 11 ; K, 19 ; Ca, 20 ;
Mg, 12 ; O, 8 ; Cl, 17 ; S, 16]
 Lithium oxide,
 Sodium sulphide,
 Calcium chloride,
 Magnesium oxide,

18. Try this out
 Draw the electron arrangements of the
formation
 Hydrogen chloride
 Water
 tetrachloromethane

19. Try this out
 Draw the electron arrangements of the
formation
 Carbon dioxide
 Ammonia (NH3)

20. The Properties of Ionic and
Covalent Compounds
Ionic compound
 Exist as solid
 High. ->Non-volatile
 Conduct electricity in
aqueous
solution/molten
state
 Dissolve in water &
do not dissolve in
organic solvents
Covalent Compound
 Exist as solids, liquid
or gases
 Low. ->volatile
 Do not conduct
electricity
 Dissolve in organic
solvents and do not
dissolve in water
Physical state
at room
temperature
Melting &
boiling point
Electricial
conductivity
Solubility

21. Electrical conductivity – ionic compounds
 Do not conduct electricity in solid.
 Ions are fixed in positions in the crystal lattice
structure
 Ions do not move freely
 Conduct electricity in molten or aqueous
solution
 Ions are free to move
Why?

22. Electrical Conductivity – covalent compounds
 Do not conduct electricity in all states
 Consist of neutral molecules
Why?

23. Melting and Boiling Points
 Ionic compounds have high melting and boiling
points.
 Ions are held together by strong ionic bonds.
 A lot of energy is needed to overcome the strong
electrostatic forces between the ions
 Covalent compounds
 Have low melting and boiling points
 Consist of molecules that held together by weak
intermolecular forces
 Less heat is required to overcome these forces

24. Use of covalent compounds
 Most covalent compounds are good solvents with
high volatility
 Example:
 Alcohol
 Acetone
 Ether
 Hexane
 Used in
 Cosmetics
 Medical
 industries

25. The End
Good luck in the exam!