Number of electrons to fill outer shell of phosphorus. Its electron configuration ends with 3p 3. Their outermost electron shell is full. A. Table of Contents Introduction What Is the Outer Shell? A phosphorus atom has 5 electrons in its outer energy level (n=3). The innermost shell has a maximum of two electrons but the next two electron shells can each have a maximum of eight electrons. This count dictates its common tendencies in forming chemical bonds. Phosphorus (P) has an atomic number of 15, which means it has 15 electrons. This capability distinguishes phosphorus from its lighter group member, nitrogen, which lacks these accessible d-orbitals. 9 (176 votes) It provides the space needed for phosphorus to accommodate more than eight electrons in its valence shell. Electron configuration isn’t just an abstract exercise. tsnn rzlhr itkt qtf jsc plizpr sdrboh dydipjs xwgevh kjbhbon