The size and shape of an electron cloud are most closely related to the energy level and sublevel of the electrons within that cloud. Here's why:

* Energy Level: The higher the energy level of an electron, the further away it is from the nucleus on average. This means the electron cloud will be larger.

* Sublevel: The shape of the electron cloud is determined by the sublevel (s, p, d, or f) the electron occupies.

* s sublevel: Spherical shape.

* p sublevel: Dumbbell shape.

* d and f sublevels: More complex, multi-lobed shapes.

In summary: The energy level dictates the overall size of the electron cloud, while the sublevel dictates its shape.