Interparticle interaction in condensed media: some elements are 'more equal than others'

Some aspects of interparticle and intermolecular interaction in condensed media are discussed, with special emphasis on hydrogen bonding (intermolecular interaction involving hydrogen atoms) and chemical bonds between carbon atoms. The intermediate strength of hydrogen bond is due to the hydrogen atom having no inner-shell electrons ('zero-sized ion'). Hydrogen-bonded substances exhibit a large number of modifications and aggregate states at or near normal temperature and pressure conditions. The diversity of carbon structures and the uniquely strong interatomic interaction they exhibit is determined by the position of carbon in the Periodic Table (the middle of the second period). The simultaneous presence of hydrogen and carbon atoms in substances leads to a huge variety of possible states (including metastable ones) for organic substances. The region of existence of 'complex' organics lies in a rather narrow temperature-pressure range of 100-1000 K and 0-1 GPa.