Periodic Table Apartment(PTA)

This is the Periodic-Table-Apartment(PTA) that a lot of Little elements live in.


The character is similar to the other Little Elements who live in a lengthwise line.
We're calling the Little Elements which live in the light blue room at the left end in the apartment alkali metal.

The alkali metal has an extra electron and wants to give it to other Little Elements.
Especially, the halogen elements who live in the red room at second right side in the apartment would like to get another electron.
So, the alkali metal and the halogen element is likely to get along together.  They don't like to be deserted.. If you try to divide the couple, you have to give much more effort to them.