And we'll see that this directly translates into something called electronegativity. So let's look at the third periodic trend called electronegativity. Now, electronegativity is simply the ability of atoms to accept or attract other electrons. And we see that as we go from left to right, across the period, from Lithium to Fluorine, our Electronegativity increases. So let's examine why. Let's look at atomic structure and the electron configuration of lithium and compare to that of fluorine.