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. The term "particles" is just a general term used for ions, atoms, molecules, or formula units. We talked about each of these four terms above. If we want to combine them all into one idea, we can use the term "particles". Here we state that 1 mole of a substance is equivalent to Avogadro's number, right? So, that would mean that 1 mole of chlorine, and remember chlorine is a diatomic element in its natural form, equals 6.022×1023 molecules of Cl₂.

We need to realize that this can be a conversion factor because it combines two different units together. We can state that 1 mole of Cl₂ is 6.022×1023 molecules of Cl₂. And remember, with conversion factors, we can use the reciprocal by flipping it. So, we could state 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 bit more. We have one mole of chlorine, which in its natural form is Cl₂. Why are we using the term "molecules", though?

Remember, 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 are using the term "molecules". That's why we're 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 because we would only use the term atom if it was just one chlorine by itself. We can't use the term formula unit because a formula unit would imply that we need to have a metal connected to that chlorine, as formula units denote a metal and a nonmetal together. Again, if we're trying to go between moles and particles, we have to utilize Avogadro's number, and we are using the term "molecules" here because we have two nonmetals together.