What's the amount of electrons on each electron shell

Each energy level (shell) has more subshells available to it: The first shell only has the s subshell ⟹ 2 electrons. The second shell has the s and p subshells ⟹ 2 + 6 = 8 electrons. The third shell has the s, p, and d subshells ⟹ 2 + 6 + 10 = 18 electrons.

You start with 2 on the inside and add two to each shell each time

This type of galaxy is an approximately ellipsoidal shape and a smooth, nearly featureless image. they are the largest single star systems, in the universe and are built by the collisions of many smaller galaxies.