What are inner transition metals?
They are called the Lanthanoid series and the actinoid series (more commonly known as the f-block). The f-block follows periods of similar atomic number rather than groups of similar electron configuration. They are those two groups that are usually taken out of the periodic table and put at the bottom of the table or else the table would be too wide. That is why they are called the “inner” transition metals because they are supposed to fit in with other transition metals. If you look at the periodic table, then you will see the two empty spaces where they are supposed to go. But the wide periodic table shows how the table would look if they were included in the main part of the table.
