Chemistry Module Form 4 (5)

mohd faisol mansor/chemistry form 4/chapter 5

79

CHAPTER 5 CHEMICAL BONDS

Atom of other

element that have

less than eight

valence electron

are not stable

Almost all chemical

substances exist as

compounds in nature

except inert gases

and other stable

element (such as

gold and silver).

Less stable atom

will tend to release,

accept or share

electron to

achieve the stable

electron

arrangement

of an inert gas.

All other elements

combine together to

achieve the stability by

forming duplet or octet

electron arrangement by

i) The transfer of electron

ii) Sharing of electron

Two types of chemical

bonds formed:-

i) ionic bonds

ii) covalent bond

Covalent Bond

Ionic Bond


80

Ionic Bond

Ionic bond formed

when metal atom

transfer electrons to

non-metal atom to

form ionic

compound.

Formation of

Cation

Formation of

Anion

Metal atom from

group 1,2 and 13

tend to released all

their valence

electrons.

Non-Metal atom

from group 15, 16

and 17 tend to

accept the

electrons.

Example:

Draw the formation

of sodium ion.


81

1. Draw the formation of the following cations:

a) Potassium ion

b) Magnesium ion

c) Aluminium ion

Exercise


82

2. Draw the formation of the following anions:

a) Chloride ion

b) Oxide ion

c) Nitride ion


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Formation of Ionic Compound

Example: Formation of Sodium Chloride, NaCl

[Write in general about the formation of ionic compound]


84

1. Explain the formation of ionic compound below:

a) Lithium fluoride

b) Magnesium oxide

Exercise


85

c) Calcium chloride

d) Aluminium oxide


86

2. Draw the formation of the following ionic compound:

a) Lithium fluoride

b) Magnesium oxide


87

c) Calcium chloride

d) Aluminium oxide


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Ionic Equations

Equation that represent the formation of ionic compounds are

known as ionic equation.

Example:

a) Formation of sodium chloride, NaCl

i) Chemical Equation :

ii) Half-ionic Equation :

b) Formation of Magnesium oxide, MgO

i) Chemical Equation :

ii) Half-ionic Equation :

1. Write an ionic equation of the following compound

a) Lithium fluoride

b) Magnesium chloride

c) Aluminium oxide

Exercise


89

1. Atom X and Y each have proton numbers of 3 and 8. What is

the ionic compound formula formed between atoms X and Y?

2. Complete each of the following table:

Atom Proton

Number

Electron

Arrangement

Ionic

Formula Atom

Proton

Number

Electron

Arrangement

Ionic

Formula

Compound

Formula

A 3 B 9

1 C 11 D 8

2 E 12 F 17

3 G 20 H 9

4 I 19 J 17

5 K 13 L 8

6 M 13 N 17

Exercise


90

Covalent Bond

Covalent bond is the

chemical bond

formed through the

sharing of electron

between two or more

non metal atom to

form covalent

compound.

Three types of covalent

bonds:

single covalent bond

( sharing one pair of e )

double covalent bond

( sharing two pairs of e )

triple covalent bond

( sharing three pairs of e )

Single Covalent Bond

Example:

Draw the formation of chlorine gas.


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Double Covalent Bond

Example:

Draw the formation of oxygen gas.

Triple Covalent Bond

Example:

Draw the formation of nitrogen gas.


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1. Draw the formation of the following compound.

a) water

b) Carbon dioxide

Exercise


93

c) Ammonia

b) Tetrachloromethane , CCl4.


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Determine the Formula of Covalent Compound

Guideline:

1. State the electron configuration of atoms.

- Make sure electron valence for both atoms is either 4, 5, 6, and 7.

2. Determine the number of electrons needed to achieve stability.

3. Write the number of electron needed to achieve stability at the

below right corner of each atom.

4. Cross the number.

Example:

If atom P has 8 protons and atom Q has 9 protons, determine the

formula of the covalent compound formed.


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1. Atoms K and S each have a proton number of 6 and 8

respectively. What is the formula of the covalent compound

which is formed by K and S?

2. Complete the table below to show the formulae of compounds

which are formed.

Atom Proton

number

Electron

config. Atom

Proton

number

Electron

config.

Compound

formula

A 6 2.4 B 9 2.7 AB4

C 6

D 16

E 7

F 1

G 1

H 8

I 6

J 17

K 6

L 8

Exercise


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Comparison between the formation of the ionic bond and the

covalent bond

IONIC BOND COVALENT BOND

Similarity

Differences

Formation

Particles

Force of

Attraction


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The following figure compares and contrasts the properties

of ionic compound and covalent compound

IONIC COMPOUND COVALENT COMPOUND

PROPERTIES

Physical State

Melting &

Boiling point

Solubility

Electric

Conductivity


98

1. (a) Table 1.1 shows the proton number of three elements, X, Y, and

Z. The letters used do not represent the actual symbols of the

elements.

Element Proton Number

X 6

Y 12

Z 17

Table 1.1

i) Write the electron arrangement of:

Atom Y : _______________________________________________

The ion of Z : ___________________________________________

ii) Write the formula of the compound formed between

elements Y and Z.

________________________________________________________

iii) Element X reacts with element Z to form a covalent

compound with a formula XZ4. State two physical

properties of this compound.

________________________________________________________

________________________________________________________

i) Draw the electronic structure of the compound XZ4.

Exercise


99

(b) Table 1.2 shows some physical properties of two compounds, U

and V.

Compound Melting pt

(oC)

Boiling pt

(oC)

Solubility in

water

Solubility in

organic

solvent

U 800 1 420 Soluble Insoluble

V - 95 86 Insoluble Soluble

Table 1.2

i) State the physical state of the following compound at room

condition.

U : _______________________________________________________

V : _______________________________________________________

ii) State the type of compound for U.

__________________________________________________________

iii) Explain why melting point and boiling point of compound U is

higher than V?

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

Chemistry Module Form 4 (5)

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