Lesson Notes By Weeks and Term v4 - SHS 3

Lesson Video

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Performance objectives

• Define the mole and its significance in chemistry.
• Describe different elementary entities like atoms, molecules, and ions.
• Relate the mole to Avogadro’s Constant.
• Solve problems converting between moles, mass, and number of particles.

Lesson summary

Welcome, learners. In our daily lives, we use special words to count large quantities of items. For example, we buy a "dozen" eggs (12 eggs) or a "ream" of paper (500 sheets). In chemistry, we deal with particles like atoms and molecules that are incredibly small and exist in unimaginably large numbers. It is impossible to count them one by one. To solve this, chemists invented a special counting unit called the mole. Understanding the mole is the foundation for almost all chemical calculations, from making medicines in our pharmaceutical companies in Tema to producing the right fertilizers for our cocoa farms.

Lesson notes

A. Why Do We Need a Special Unit? The Chemist's Dozen

Imagine you are asked to count the grains of gari in a bowl. It would be an impossible task! Now, imagine trying to count the number of water molecules in a single drop of water. The number is astronomical.

Chemists face this problem every day. The particles they work with—atoms, molecules, ions—are too numerous to count individually. To handle these huge numbers, they use a unit called the mole. Just like 1 dozen always means 12 items (e.g., 1 dozen eggs = 12 eggs). Just like 1 pair always means 2 items (e.g., 1 pair of shoes = 2 shoes).

In chemistry: 1 mole always means a specific, very large number of items. B. The Mole (symbol: mol)

Evaluation guide

• Describe the mole as a unit of amount of substance.
• T
• alkforLearning: Through a class activity:
• Explain the mole in relation to various elementary entities (atoms, ions, molecules, electrons,