Microscopic structure
Energy materials

From the above, it's clear that certain types of material cannot provide good candidates as energetic materials. In a substance whose atoms all have comparable electronegativity (in particular, if it consists of a single element), no significant energy gain can be achieved by electron exchange (unless these atoms have different oxidation states, such as the nitrogen atoms of the azide groups —N ₃ ). On the other hand, an energetic material cannot be metallic, as the mobility of electrons in a metal allows them to adopt their minimum energy distribution. Similarly, the interactions between atoms in covalent inorganic solids (such as oxides) allow electronic exchange through bonding.