When atoms of different types combine to form molecules, it is a heteroatomic molecule. For example, when Carbon (C) and Oxygen (O) atoms combine under an appropriate reaction condition, it can lead to the formation of two types of products (carbon monoxide, CO, and carbon dioxide, CO2) containing two types of atoms.
A heteroatomic molecule can be diatomic (like hydrogen chloride, HCl), triatomic (like water, H2O), or polyatomic (like methane, CH4).
When the atoms combining to form molecules are of the same type, it is a homoatomic molecule. For example, when two Hydrogen atoms (2H) combine under an appropriate reaction condition, a Hydrogen molecule (H2) is formed.
A homoatomic molecule can be diatomic (like elemental hydrogen, H2), triatomic (like ozone, O3), or polyatomic (like sulphur allotrope, S8).
Heterolytic cleavage or heterolysis is a chemical reaction in which the bond between two atoms breaks unequally so that the two bond electrons reside with only one atom.
The atom that receives both electrons become an electron-rich negatively charged ion (anion, denoted with a negative sign), and the atom that lost the electrons forms a positively charged ion (cation, denoted with a positive sign).
Homolytic cleavage, or homolysis, is a chemical reaction in which a covalent bond between two atoms is broken equally, and each atom retains one of the two electrons that form the bond. This creates two species (similar or dissimilar), each with an unpaired electron, known as the radicals. The radical electron is denoted with a dot (.) over the atoms’ symbol.
Hydrogen bonding is an attractive intermolecular interaction stronger than Vander Waals forces that exclusively occurs when the Hydrogen atom is sandwiched between two highly electronegative atoms N, O, or F, one to which it is covalently bonded and the other it attracts electrostatically.