A phosphorus (P) atom has five valence electrons. Phosphorus is in Group 15 of the periodic table, also known as Group V or Group 5A. Elements in this group have five valence electrons because they are located in the fifth column of the periodic table. Valence electrons are the electrons in the outermost energy level or shell of an atom, and in the case of phosphorus, there are five electrons in the outermost shell.