Provide an example of the atomic radius and ionic radius.

The atomic radius is the distance from the nucleus to the outermost electron shell of an atom, while the ionic radius is the distance from the nucleus to the outermost electron shell of an ion.

The atomic radius of an element increases as you move down a group in the periodic table because the number of electron shells increases. It also decreases as you move across a period because the number of protons in the nucleus increases, pulling the electrons closer to the nucleus.

The ionic radius of an ion depends on the number of electrons it has compared to its neutral atom. If an ion has lost electrons, it becomes positively charged and its ionic radius decreases because there are fewer electrons to repel each other. If an ion has gained electrons, it becomes negatively charged and its ionic radius increases because there are more electrons to repel each other.

For example, the atomic radius of sodium (Na) is larger than the atomic radius of chlorine (Cl) because Na has one more electron shell than Cl. When sodium loses an electron to become a Na+ ion, its ionic radius decreases because there are fewer electrons to repel each other. When chlorine gains an electron to become a Cl- ion, its ionic radius increases because there are more electrons to repel each other.

Understanding atomic and ionic radii is important in predicting chemical reactions and understanding the properties of elements and compounds.