Electron configuration

-there are 7 periods in electron configuration (1,2,3,4,5,6,7)

-there are 4 sublevels (s,p,d,f)

-s can have 2 e max, p can have 6 e max, d can have 10 e max, f can have 14 e max

-How to write: you start with s and fill it with electrons, then fill all the levels and sublevels depending on the atomic number, configurations may also differ when an element is ionized

-When writing condensed forms, you simply use the noble gas before the element (He, Ne, etc.)

-When eliminating of adding electrons, you always start with s, and then p and then d,lastly f

-There are exceptions in writing configurations: Cr and Cu since they are written with 4s1 3d5, Cr [Ar] 4s13d5, Cu [Ar] 4s13d10, this happens to improve stability and lowers overall energy of the element