So when we look at molecular compounds, we're going to see discrete molecular
units, and these are between two non-metallic elements.
Remember that when we talk about molecular compounds,
we can't predict their formulas like we can for ionic compounds,
because there are different ways for those electrons to be shared between atoms.
And as a result, we can have different numbers of each type of atoms.
We talked about our example with nitrogen and
oxygen that we could have NO, NO2, N2O4, N2O5.
Lots of different options for how to name those compounds, and so
we have to have something in the name of molecular compounds that tells
us how many of each type of atom we actually have in that unit.
Now most of these are going to be binary compounds,
meaning they contain two different elements.
We could have many more than two atoms, but they'll only contain two elements.
There are some exceptions but
we're not going to be getting into those in this course.