So thus far we have combined a one S orbital and a one S orbital. And we've also combined a one S with a two P. In this lecture, we're going to combine a two p with a two P to four molecular orbitals. Now, the first thing we have to realize is that there are at least two different ways that we can orient our two p orbitals. In part A, we have a parallel orientation. In other words, our two p orbitals are simply parallel to one another. In Part B, we have an orthogonal or perpendicular orientation in which our one two p orbital is perpendicular to our second two p orbital.