Each period of the periodic table ends with: Seven orbital shells the oxygen family group VIIIA elements alkali metals such as Na, K, Li, and Cs period 7 elements

Each period of the periodic table ends with the group VIIIA elements, which are also known as the noble gases. These elements include helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn). Noble gases are characterized by their full valence electron shells, making them very stable and unreactive.