Lecture 1 – Introduction

ACKNOWLEDGEMENT:

Figure	Source of Figure
Figure 1	www.bbc.co.uk

Mole:

Mole is defined as the amount of substance that contains the Avogadro number of particles.

Note: particles can be atoms or molecules

Avogadro number:

Avogadro number is defined as the number of atoms present in 12g of Carbon 12 isotope. It is equal to 6.02 x 10²³.

1 mole = 6.02 x 10²³ particles

1 mole of C - 12 = 6.02 x 10²³ particles of C - 12

Mole & its relation with Relative atomic mass:

Mole for elements is expressed as the relative atomic mass of the element in grams.

Table 1:

1 mole of an element	Element’s Ar in Grams
1 mole of Carbon	12g
1 mole of Sodium	23g
1 mole of Neon	20g

Mole & its relation with Relative molecular mass:

Mole for compounds is expressed as the relative molecular mass of the compound in grams.

Table 2:

1 mole of a compound	Compound’s Mr in Grams
1 mole of Carbon dioxide	44g
1 mole of Sodium chloride	58.5g
1 mole of Oxygen	32g

Note: Oxygen is an element, but it exists naturally in the form of O₂ – diatomic molecules:

Figure 1:  

Mr of O₂ = 16g + 16g = 32g

1 mole of O₂ = 6.02 x 10²³ molecules of O₂

Note: Each molecule of O₂ is made up of 2 atoms of Oxygen, therefore:

1 mole of O₂ = 2 x 6.02 x 10²³ atoms of O