As previously discussed, phosphorene has a very unique structure. Due to the lone pairs on each phosphorus atom and the three covalent bonds formed to other phosphorus atoms, each atom is sp 3 hybridized, forming a trigonal pyramidal structure. This leads to a puckered orthorhombic structure in each elemental sheet, creating a third dimension in each layer unlike other commonly discussed 2D materials like graphene. Most importantly, this puckered structure leads to decreased symmetry within the material, which allows for the higher prevalence of anisotropic properties. We see the effect of the orthorhombic structure in Fig. where there is virtually no isotropic regime within the stress-strain and elastic energy curves.