Each of the orbitals has a different shape. The s orbitals are spherical and the p orbitals are dumbbell shaped.
Core and Valence electrons
Electrons in the outermost energy level of an atom are called valence electrons. The electrons that are in the energy shells closer to the nucleus are called core electrons. Core electrons are all the electrons in an atom, excluding the valence electrons. An element that has its valence energy level full is more stable and less likely to react than other elements with a valence energy level that is not full.
Definition: Valence Electrons
The electrons in the outermost energy level of an atom.
Definition: Core Electrons
All the electrons in an atom, excluding the valence electrons.