"Electron Configuration is the arrangement of electrons around the nucleus of an atom in its ground state."1 There are four sublevels of electron configuration and they are s, p, d, and f. The s and the p sublevels are the outer most sublevels. The s sublevel is on the left side of the table and contains the two groups Alkali metals and Alkaline Earth Metals. It takes 2 electrons to fill the s sublevel. It 6 electrons to fill the p sublevel and it consists of the groups Aluminum, Carbon, Nitrogen, Oxygen, Halogens, and Noble Gases. Here is a examples of Electron Configuration using s and p sublevels.
Ar= 1s2 2s2 2p6 3s2 3p6
The transition metals group is the d sublevel group and it takes 10 electrons to fill the d sublevel. Here is a example of Electron Configuration using the d sublevel.
Fe= 1s2 2s2 2p6 3s2 3p6 4s2 3d10
The last sublevel is the f sublevel and it takes 14 electrons to fill it. It is part of the transition metal group, but it is called the inner transition metals. The are the two rows of Lanthanide and Actinide. Here is an example of Electron Configuration using the f sublevel.
Source: The text on my page was taken from the book, "Addison-Wesley Chemistry", Addison-Wesley Chemistry, SI Edition Copyright 1993 Addison-Wesley Chemistry Publisher Limited.