Final answer:
As you go down a column of the periodic table, the atomic radii increase due to the larger principal quantum number and the valence electron shell getting larger.
Step-by-step explanation:
As you go down a column of the periodic table, the atomic radii increase. This is because the valence electron shell is getting larger and there is a larger principal quantum number, so the valence shell lies physically farther away from the nucleus. This trend can be summarized as follows:
- The atomic radius generally increases down a group.
- As the atomic number increases down a group, there is an increase in the number of occupied principal energy levels. Higher principal energy levels consist of orbitals that are larger in size than the orbitals from lower energy levels.