Electronic Configurations TABLE 2.2 Electronic Configurations for the Atoms of Some Elements Found in Living Organisms(continued) Number First Second Third of Valence Number Maximum Electron Electron Electron (Outermost) of Unfilled Number of Element Shell Shell Shell Diagram Shell Electrons Spaces Bonds Formed Magnesium 2 2 2 Phosphorus 2 Sulfur 2 6 2 electron Cunfilled space Key:atomic nucleus Table 2.2.2 Electronic Configurations Table 2.2.2