How to find ionic radius? Trends of ionic radius in periodic table.

On what factors does ionic radius depends on?

Dear student 

As the atomic number increases, the ionic radius increases. As the atomic number increases, the first ionization energy decreases. These trends both exists because as we proceed down the group, the size of the atom increases due to addition of an electron shell.
the ionic radius decreases for metals forming cations, as the metals lose their outer electron orbitals. The ionic radius increases for nonmetals as the effective nuclear charge decreases due to the number of electrons exceeding the number of protons.
Neither the atomic radius nor the ionic radius of an atom is a fixed value. The configuration or stacking of atoms and ions affects the distance between their nuclei. The electron shells of atoms can overlap each other and do so by different distances, depending on the circumstances.