3. Polonium, in its two polymorphs at RP (α-Po and β-Po), is the only element, together with tetragonal boron , that exhibits EDMBs at RP. Remarkably, Po is the only element with all bonds being fully EDMBs at RP, unlike tetragonal boron, which exhibits a mixture of EDMBs and covalent bonds. Since EDMBs are softer than covalent bonds, one can understand the low melting temperature of Po, which has been considered a common metal or semimetal, despite it displays the octahedral coordination of incipient metals .