1. TOPIC 5 CHEMICAL BONDS By: School of Allied Health Sciences
City University College of Science and Technology

2. Formation of compounds
Elements form compound because compounds are more stable than elements
Only inert gases DO NOT form compound because they have STABLE electron arrangements
A duplet or octet electron arrangement is VERY STABLE. They DO NOT release, accept or share electrons with other elements.
Two example of chemical bonds are:
Ionic bonds (transfer of electron)
Covalent bonds (sharing electron)

3. Most of these elements have completely-filled valence e-
Noble Gases
Group 18 (noble gases) are VERY stable because:
Most of these elements have completely-filled valence e-
Example :
He = valence e-
DUPLET of e-
Ne = valence e-
OCTET of e-

4. Formation of ions Ions - Charged particles Cation Anion Charge +ve -ve
Formed by
Releases electron
Accept electron
Element
Metal
Non metal
Groups
Group 1, 2 and 13
Group 15, 16 and 17
Release all valence electron to achieve octet arrangement
Accept electron to achieve stable octet arrangement
Example
Cu2+, K+, Al3+
Cl-, O2-,

5. Formation of ionic bonds
Formed from the transfer of electron
Metal + Non metal  Ionic compounds
Formation of ionic bonds
Electron are transferred from a metal to a non-metal atom.
Metal atoms release valence electron to form +ve ion
Non metal atoms accept electrons to form –ve ions
+ve ions and –ve ions are attracted to each other by string electrostatic force of attraction

6. Formation of ionic bond in sodium chloride, NaCl
Na atom release valence electron to form octet
Na  Na+ +e
Chlorine atom accept electron to form octet
Cl e  Cl-

7. Formation of covalent bonds
Formed from the sharing of electron between non metal and non metal atom.
Hydrogen, Group 14, 15, 16 and 17
Three types of covalent bonds
Single bond – One pair of electron shared
Double bonds – Two pairs of electron shared
Triple bonds – Three pairs of electron shared

8. Double bond
Single bond
Triple bond

9. Formation of hydrogen molecule, H2
Hydrogen atom needs to share one electron to achieve stable duplet electron arrangement
One pair of electrons forms a single covalent bonds.

10. Formation of oxygen molecule, O2
Oxygen atom with electron arrangement 2.6 needs to share two electrons to achieve octet 2.8
The sharing two pairs of electrons forms a double bond.

11. Formation of nitrogen molecule, N2
Nitrogen atom with an electron arrangement of 2.5 will contribute three valence electrons to be shared to achieve stable octet electron arrangement
Three pairs of electrons forms triple bonds

12. Formation of tetrachloromethane, CCl4
Carbon atom with electron arrangement 2.4 needs to share four electrons to achieve octet
Chlorine atom with electron arrangement needs to share one electron to achieve octet

13. PyQx C1Cl4 = CCl4 Formula of ionic compound Mb+ + Xa-  MaXb
Eg: Al O2-  Al2O3
Formula of covalent compound
PyQx
Eg: CCl4
-Carbon needs 4 electron shared to
achieve octet
-Chlorine needs 1 electron shared to
Num of electron shared by P
Num of electron shared by Q
C1Cl4
Four electron shared by carbon
One electron shared by chlorine
= CCl4

14. Ionic vs Covalent bonding
Characteristic
Ionic bonding
Covalent bonding
Elements
Between metals
(Groups 1, 2, 13) and non metals (Groups 15, 16, 17)
Between non-metal and non-metal (Groups 14, 15, 16, 17, H)
Bond formation
Transfer of electrons
Sharing of electron
Types of particles
Positively and negatively charged ions are formed
Molecules are formed (No charged ions)
Force between particles
Strong force of attraction
Weak intermolecular forces of attraction between molecules

15. Properties of ionic and covalent compound
Ionic compound
Covalent compound
Melting point,
Boiling point and volatility
High melting and boiling point,
Non-volatile
Low melting and boiling point, volatile
Solubility
Usually soluble in water but insoluble in organic solvent
Usually soluble in organic solvents but insoluble in water
Electrical conductivity
Conducts electricity in the molten or aqueos state
Not conduct electricity in any state

16. THANK YOU….