Now in order to convert between moles and particles, we have to utilize what's called Avogadro's number. Avogadro's number states that 1 mole of a substance is equal to 6.022×1023 particles. This value of 6.022×1023, that is Avogadro's number. When we say the term particles, it's just a general term used for ions, atoms, molecules, or formula units. If we want to combine them all into one idea, we can use the term particles.

We are going to say here that 1 mole of a substance is equal to Avogadro's number. Right? So, that would mean that 1 mole of chlorine, remember chlorine is a diatomic element in its natural form, equals 6.022×1023 molecules of Cl2. We need to realize here that this can be a conversion factor because it's combining two different units together. So we can say here that 1 mole of Cl2 is 6.022×1023 molecules of Cl2. And remember, conversion factors allow us to do the reciprocal, where we flip it. So, we could say Avogadro's number on top, moles of Cl2 on the bottom, depending on if we want units to cancel out in a certain way.

Before we move on to the next section, let's investigate this conversion factor a little more. We have one mole of chlorine, which in its natural form is Cl2. We are using the term molecules because the term molecules is used when we have a compound that has two or more nonmetals together. Chlorine is a nonmetal, and there are two of them. That's why we're using the term molecules, not using ions, atoms, or formula units. It can't be an ion because it doesn't possess a positive or negative charge. It can't be an atom, as we would only use the term atom if it was just one chlorine by itself. We can't use the term formula unit because formula units imply a metal connected to the nonmetal, which is not the case here. So, again, if we're trying to go between moles and particles, we have to utilize Avogadro's number, and we're using the term molecules here because we have two nonmetals together.