Introduction

These days, medicines come from a variety of sources. Many were developed from substances found in nature, and even today many are extracted from plants. But, how do we form the rightful amount of medicine that we need? In order to make the drug form its ingredients, someone has to figure out how much of each ingredient is needed to react together to make the final drug. This will prevent us from having drug overdose, or taking too much from a substance which can result to abnormal breathing, loss of consciousness, and worse may lead to death.

In the laboratory, chemists measure out a chemical substance and react it with another substance to form the desired quantity of a new product. In this case, chemists want to know the number of atoms, ions or molecules because these are the ones that react with each other. However, these things are too small and too many to count individually so chemists use a unit called mole to count them by weighing. Like a dozen, a ream, or a case, a mole also represents a certain number of particles. Can you guess how many particles are equal to one mole?

In this lesson, you will be able to understand the mole concept and Avogadro’s number. In addition, you will be able to learn conversion among moles, mass and number of atoms in a given sample.

Let us explore on what you already know about moles. To do this, answer this short pretest  before you go through the rest of this study material. 

When you're done taking the pretest, you may proceed to the lesson on The Mole.