A molecule is defined as the smallest unit of a chemical compound that retains the chemical properties of that compound. These fundamental particles are formed when two or more atoms are chemically bonded together. The composition of a molecule can range from having atoms of the same element, such as diatomic oxygen ($\text{O}_2$), to having atoms of entirely different elements, forming compounds like water ($\text{H}_2\text{O}$). Molecular interactions underpin all known chemical and biological processes, determining the structure and function of matter. The study of molecular structure and bonding is central to chemistry and provides the basis for understanding materials science, biochemistry, and physical properties.