Molecules and Compounds

In nature, all matter is comprised of basic chemical units called elements having specific physical and chemical properties.

The periodic table lists a total of 118 elements identified to date. The constituent unit of each element is the atom. Some elements like helium, neon, silver, or platinum exist as units of independent individual atoms.

Other elements like hydrogen, oxygen, or sulfur exist as units of two or more identical atoms. These multiple atoms are held together by strong electrostatic forces referred to as chemical bonds, forming stable units called molecules.

Additionally, two or more different elements can also combine to form molecules like water or fructose. Such molecules that are formed by the combination of atoms of two or more elements, united chemically in a fixed proportion, are also called compounds. Hence, water and fructose molecules are also compounds.

Water is a molecule formed of two atoms of hydrogen and one atom of oxygen. In contrast, fructose is a molecule that contains six carbon atoms, twelve hydrogen atoms, and six oxygen atoms.

The individual atoms within a compound are held together by chemical bonds, dictating the type of compound formed such as a molecular or ionic compound.

Covalent or molecular compounds, like water, form when nonmetal atoms come together and share their valence electrons via a covalent bond. The shared electrons between two atoms lower the potential energy and create more stable molecules compared to the individual atoms.

Ionic compounds, like sodium chloride, form when metal and nonmetal atoms come together. Metals easily lose electrons becoming cations, while nonmetals readily gain electrons becoming anions. Thus metal atoms transfer electrons to nonmetal atoms and the electrostatic interactions between the oppositely charged ions form ionic bonds.

The ability of elements to form compounds contributes to the great diversity of matter that exists in nature.