Of course the electrons in the 3s orbitals are even farther out from the nucleus, so we would expect Na to be even more reactive than Li, and so on for K, Rb, etc. On the other hand Cl will also attract electrons less than F, so it will be less reactive etc. So we will expect the most reactive elements to be on the opposite corners of the table - lower left and upper right. There are a number of different notation conventions for electronic configurations. Note also that you may write them in the order they show up on the Periodic Table, or, if you prefer, you may group them by shell Spectroscopic notation using the Noble gas core convention .
Electrons fill atoms by sequentially filling hydrogen-like orbitals in order of energy.
Use to predict electron patterns in atoms. But there are some variations, since in fact we are also adding charge to nucleus. In orbital filling diagrams we provide a little more information - noting that the electrons come in two different spins and that they fill into orbitals with their spins paired in opposite directions. I have no preference for the direction of unpaired arrows other than that they should be the same. Orbital Filling Diagrams using the Noble gas core convention .