Hydrogen bond
Hydrogen bonds can be intermolecular (occurring between separate molecules) or intramolecular (occurring among parts of the same molecule). Depending on the nature of the donor and acceptor atoms which constitute the bond, their geometry, and environment, the energy of a hydrogen bond can vary between 1 and 40 kcal/mol. This makes them somewhat stronger than a van der Waals interaction, and weaker than fully covalent or ionic bonds. This type of bond can occur in inorganic molecules such as water and in organic molecules like DNA and proteins.
Chalcogen bond
Due to a chalcogen's ability to function as an electron donor, many systems will balance between hydrogen bonding with the chalcogen as a donor or chalcogen bonding. This balance can be observed in a series of self-bonding intermolecular interactions between various substituted chalcogens. In cases with hard chalcogen atoms as acceptors, the balance favors H-bonding between chalcogen and methyl H. However, as the acceptor atoms move down the group, chalcogen-chalcogen bonding will be favored. It is hypothesized that electrostatic forces should only dominate in a chalcogen-chalcogen bond with lighter congeners, and instead that dispersion forces dominate in the cases of heavier congeners