Writing Electron Configurations Using the Periodic Table

3 Writing Electron Configurations Using the Periodic Table 

To discuss bonding and the chemistry of the elements coherently, you must be able to reproduce the atomic configurations with ease, following the building-up principle. All you need is some facility in recall of the building-up order of subshells. 

You read the building-up order by starting with the first period, in which the Is subshell is being filled. In the second period, you have 2s (violet area) then, staying in the same period but jumping across, you have 2p (blue area). In the third period, you have 3.s and 3p in the fourth period, 4s (violet area), 3d (red area), and 4p (blue area). This pattern should become clear enough to visualize with a periodic table that is not labeled with the subshells, such as the one on the inside front 

The colored areas of elements show the different subshells that are filling with those elements. 

Determining the Configuration of an Atom Using the Building-Up Principle 

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