CHEMISTRY FORM 4 KSSM 2021 CHAPTER 5 : CHEMICAL BONDS IONIC BONDS AND COVALENT BOND

1. CHAPTER 5
CHEMICAL BONDS

2. 5.1.1 Explain the basic formation of compounds
 Explain the stability of inert gases
 Explain the conditions for the formation of chemical bonds
 State types of chemical bonds
5.1 Basic formation of compounds

3. Sodium, Na is reactive towards chlorine gas, Cl2 when
heated and forms a white solid.
However, no compound is formed when sodium, Na is
heated with neon gas, Ne. Why?

4. • Noble gases exists as monoatomic gases and are chemically
unreactive because they have achieved a stable duplet or octet
electron arrangement.
• However, for atoms of other elements, stability of electron
arrangement can be achieved by transferring or sharing of
electrons.

5. • Chemical bonds are formed when electron transfer or
electron sharing take place.
*Chemical bonds only involve valence electrons
Chemical bonds
Ionic bonds
-Involves transfer
of electrons
Covalent bonds
-Involves sharing of
electrons

6. 5.2.1 Explain with examples the formation of
ionic bond
 Explain formation of ions
 Write the electron arrangement of the ions formed
 Explain formation of ionic bond
 Illustrate electron arrangement of an ionic bond
 Illustrate formation of ionic bond
5.2 Ionic bond

7. Formation of ionic bond
• Ionic bond is formed through the transfer of electrons between metal
atoms and non-metal atoms.
• Metal atoms donate electrons and non-metal atoms accept electrons
to achieve stable electron arrangement.

8. Formation of ions
• When an atom donates or accepts electrons, it becomes a charged particle called an
ion.
• Metal atom that donates electrons forms a positively-charged ion called cation.
• Ex : Na+, Cu2+, Al3+
• Non-metal atom that accepts electrons forms a negatively-charged ion called anion.
• Ex : Cl-, O2-
Neutral
atom
Cation (+) Anion
(-)

9. • To achieve a stable electron arrangement, sodium
atom, Na needs to donate an electron.
• The process of donating an electron from the valence
shell of sodium atom, Na is much easier compared to
accepting seven electrons from another atom.
• After donating its valence electron, sodium ion
Na+ achieve a stable octet electron
arrangement.
• Sodium ion, Na+ has 11 protons and 10 electrons,
thus the charge for a sodium ion, Na+ is +1.
Formation of sodium ion, Na+
Half-equation for the formation of sodium ion, Na+
Na  Na+ + e-

10. • To achieve a stable electron arrangement, fluorine
atom, F needs to accept an electron.
• The process of donating one electron to the valence
shell of fluorine atom, F is much easier compared to
donating seven electrons to another atom.
• After receiving one valence electron, fluoride ion
F- achieve a stable octet electron arrangement.
• Fluorine ion, F- has 9 protons and 10 electrons,
thus the charge for a fluoride ion, F- is -1.
Formation of fluoride ion, F–
Half-equation for the formation of fluoride ion, F-
F + e- F-

11. Formation of Ionic Bond
• An ionic compound is formed when ions of opposite charges attract one another
to form an ionic bond.

13. STEPS TO EXPLAIN THE FORMATION OF IONIC BOND
FOR IONIC COMPOUND
1. Explain the formation of sodium chloride.
Sodium chloride
1. Predict the formula :

14. STEPS TO EXPLAIN THE FORMATION OF IONIC BOND
FOR IONIC COMPOUND
2. Draw the electron arrangement of the compound formed.
Element Proton
number
Electron
arrangement
Na 11 2.8.1
Cl 17 2.8.7
Sodium atom,
Na
Chlorine atom,
Cl
Sodium ion,
Na+
Chlorine atom,
Cl-
Strong electrostatic forces
between ions.

15. a) Electron arrangement of sodium atom is 2.8.1. Sodium atom has one valence electron. Sodium
atom releases one electron to achieve a stable octet electron arrangement to form sodium ion,
Na+ with electron arrangement of 2.8.
b) Electron arrangement of chlorine atom is 2.8.7. Chlorine atom has seven valence electron.
Chlorine atom receives one electron to achieve a stable octet electron arrangement to form
chloride ion, Cl- with electron arrangement of 2.8.8.
c) Sodium ions, Na+ and chloride ions, Cl- are attracted with strong electrostatic forces. The
bond formed is called ionic bond.

16. TRY THIS !
1. Explain the formation of magnesium chloride.

17. Formation of ions

18. Test Yourself 5.2, Textbook page 114
1. Aluminium atom, Al has 13 protons while fluorine atom, F has 9
protons
2. Muriate of Potash is a type fertiliser that has a high content of
potassium chloride compound. [Proton number : Cl = 17, K = 19]
a) Write the formulae of ions formed from the two atoms respectively.
b) Write half-equation for the formation of ions in (a).
a) Write the chemical formula for potassium chloride.
b) Describe the formation of ionic bonds in potassium chloride compound.

19. Formation of covalent bond

20. 5.3.1 Explain with examples the formation of
covalent bond
5.3.2 Compare ionic and covalent bonds
5.3 Covalent bond

21. 5.3.1 Explain with examples the formation of
covalent bond
 State the meaning of covalent bond
 Explain formation of covalent bond
 Illustrate the formation of covalent bond by drawing electron arrangement
 Illustrate formation of covalent bond
5.3 Covalent bond

22. Single Bond
o A single bond is formed when two atoms shared a pair of electrons.
o Example : The hydrogen molecule, H2
o A hydrogen atom has one valence electron.
o It needs one more electron to achieve duplet electron arrangement.
o Therefore two hydrogen atoms contribute one electron each for sharing.
o This shared-pair of electrons forms a single bond in the hydrogen molecule, H2.
1
Hydrogen atom, H
1
Hydrogen atom, H
+
A shared pair of electrons

23. Formation of Covalent Bond
● Covalent bonds are formed when non-metals atoms share their
electrons to achieve a stable duplet or octet electron
arrangement.
● There are three types of covalent bonds; single bond, double
bond and triple bond

24. Single Bond
Single bond
o A single covalent bond is formed when two atoms shared a pair of electrons.

25. Single Bond - Lewis Structure
● The formation of covalent bond can be visualized using the Lewis structure.
● Lewis structure only shows the valence electrons of the atoms involved.
● A pair of electrons shared is represented with a line between the two atoms.

26. Double Bond
Double bond
o A double bond is formed when two atoms share two pairs of electrons.

27. Triple Bond
Triple bond
o A triple bond is formed when two atoms share three pairs of electrons

28. EXPLAIN THE FORMATION OF CHLORINE MOLECULE
1. Chlorine atom with an electron arrangement 2.8.7 needs one electrons to achieve a stable octet electron
arrangement.
2. Two chlorine atoms share one pair of electrons to achieve a stable octet electron arrangement, forming a
chlorine molecule.
3. Each chlorine atom achieves stable octet electron arrangement.
4. The number of electron pairs shared is one pair. Single covalent bond is formed.

29. EXPLAIN THE FORMATION OF OXYGEN MOLECULE
1. Oxygen atom with an electron arrangement 2.6 needs two electrons to achieve a stable octet
electron arrangement.
2. Two oxygen atoms share two pairs of electrons to achieve a stable octet electron
arrangement, forming an oxygen molecule.
3. Each oxygen atom achieves stable octet electron arrangement.
4. The number of electron pairs shared is two pairs. Double covalent bond is formed.
2.6
Oxygen atom, O
2.6
Oxygen atom, O
Oxygen molecule, O2

30. EXPLAIN THE FORMATION OF OXYGEN MOLECULE
1. Nitrogen atom with an electron arrangement 2.5 needs three electrons to achieve a stable
octet electron arrangement.
2. Two nitrogen atoms share three pairs of electrons to achieve a stable octet electron
arrangement, forming a nitrogen molecule.
3. Each nitrogen atom achieves stable octet electron arrangement.
4. The number of electron pairs shared is three pairs. Triple covalent bond is formed.

31. FORMATION OF COVALENT COMPOUND (Hydrogen chloride, HCl)
1. Hydrogen atom with an electron arrangement 1 needs one electron to achieve a stable duplet electron arrangement.
2. Chlorine atom with an electron arrangement 2.8.7 needs one electron to achieve stable octet electron arrangement.
3. One chlorine atom shares one pair of electrons with one hydrogen atom to form hydrogen chloride molecule with
formula HCl.
4. One chlorine atom contributes one electron and one hydrogen atom contributes one electron for sharing.
5. One chlorine atom forms one single covalent bond with one hydrogen atom.
6. Chlorine atom achieves stable octet electron arrangement and hydrogen atom achieve duplet electron arrangement.

32. 5.3.2 Compare ionic and covalent bonds
 Compare and contrast formation of ionic and covalent bonds
5.3 Covalent bond

33. COMPARISON BETWEEN IONIC BOND AND COVALENT BOND
SIMILARITIES
1. Formation of ionic bond and covalent bond involves valence electrons only.
2. Atoms form ionic bond and covalent bond to achieve a stable octet electron arrangement.
DIFFERENCES
Ionic Bond Covalent Bond
Ionic bond involves transfer of electrons.
Electrons
Covalent bond involves sharing of electrons.
Electrons are released by metal atoms
and received by non-metal atoms.
Pairs of electrons are shared by the same or
different non-metal atoms.
Between metal atoms and non-metal
atoms.
Type of element
involved
Between non-metal atoms and non-metal
atoms.
Metal atoms form a positively-charged
ion.
Non-metal atoms form a negatively-
charged ion.
Type of particle
formed
Forms a molecule
Lead(II) bromide, PbBr2 ;
sodium chloride, NaCl ;
copper(II) sulphate, CuSO4
Example of ionic
and covalent
compounds
Naphthalene, C8H10 ;
Acetamide, CH3CONH2 ;
Hexane, C6H14

34. COMPARISON BETWEEN IONIC BOND AND COVALENT BOND
DIFFERENCES
Ionic Bond Covalent Bond
Electron
arrangement in the
particles.
Ionic bond is the strong electrostatic force
of attraction between positively-charged
ion and negatively-charged ion.
Covalent bond is the shared pairs of electrons
between atoms in a molecule.
Strong covalent
bond between
atoms in the
molecules.
Strong electrostatic forces
between ions
1-
1-
2+