Why are there elements on the bottom of the periodic table? What’s the name of this group of elements?

The lanthanides and actinides are separated from the rest of the periodic table, usually appearing as separate rows at the bottom. The reason for this placement has to do with the electron configurations of these elements.Groups are numbered 1–18 from left to right. The elements in group 1 are known as the alkali metals; those in group 2 are the alkaline earth metals; those in 15 are the pnictogens; those in 16 are the chalcogens; those in 17 are the halogens; and those in 18 are the noble gases.

Explanation:

Solubility would be your answer.