Concepts of Molecules

According to the concepts of molecules, the smallest particle present in a chemical compound or element is defined as a molecule. It consists of the chemical properties of the element or compound. Moreover, these are made with atoms held together with the help of chemical bonds. The formation of these bonds occurs when the sharing or exchange of electrons among atoms occurs. The atoms of some specific elements bond with other atoms to form molecules, for example, chlorine, oxygen, etc. However, some atoms of certain elements cannot easily bond with other atoms, such as argon, neon, etc.

Characteristics of Molecules

The process of dividing the sample of a substance into progressively tinier parts results in no change in either its chemical properties or its composition until the parts having single molecules are reached. Moreover, when the subdivision of the substance occurs, it results in the formation of still tinier parts that are generally different from the original substance in composition, and it always has dissimilar chemical properties. However, the chemical bonds holding the atoms together in the molecule get broken down in the later stage of fragmentation.

History of the Molecules

As the knowledge of a molecule’s structure has improved, the definition of the molecule has evolved with time. The definitions in the past were not very precise, describing the molecules as the tiniest particles of chemical substances that are pure and still retain their chemical properties and composition at the same time. This definition also becomes inappropriate as various substances in a typical experience like salts, rocks, etc., are made of vast networks of crystalline ions or atoms bonded chemically and are not made up of discrete molecules.

Molecular Bonding

The numbers of atoms that can be bonded together to form molecules have a fixed ratio. For example, every molecule of water has two hydrogen atoms and one oxygen atom. This feature makes chemical compounds different from mechanical mixtures and solutions. The hydrogen and oxygen might be available in any random proportions in the mechanical mixtures but, when sparked, will combine only in a set and prefixed proportions to form the chemical compound ‘H2O’.

The same types of atoms can combine in dissimilar but definite proportions to form different molecules, such as two hydrogen atoms that will chemically link and make a bond with one oxygen atom to produce a molecule of water. In contrast, two hydrogen atoms can chemically bond with two oxygen atoms for producing a hydrogen peroxide molecule (H2O2). Moreover, the atoms can easily and possibly bond together in similar proportions to produce different molecules known as isomers and are different only in the arrangement of the atoms inside the molecules.

Molecular Weight

The total atomic weights of the component atoms of a molecule are considered the molecular weight of the molecule. If the molecular weight is ‘M’, then one mole will be equal to ‘M’ grams of the substance. The amount or number of molecules present in a single mole is equal for all the substances, and this number is called ‘Avogadro’s number’ [6.022140857 X 1023]. Furthermore, the determination of the molecular weights can be done by kinetic transport phenomena or thermodynamics-based techniques and mass spectrometry.

Molecular Size

Many types of molecules are way too tiny to be seen without lenses, with the naked eye, while molecules of various polymers can also be of macroscopic sizes. This includes biopolymers like DNA, etc. Molecules generally used as the building blocks for organic synthesis carry a dimension of little angstroms to multiple dozen or about one billionth of a single metre. It’s not usually possible to observe single molecules through light. Still, with the use of an atomic force microscope, the outlines of individual atoms and the tiny molecules can be possibly traced in some rare cases. Macromolecules or supermolecules are a few of the biggest molecules.

Structural Formula

For the molecules with a complicated 3D structure, specifically including the atoms bonded to 4 different substituents, a semi-structural chemical formula or a simple molecular formula would not be sufficient for properly specifying the molecule. A graphical kind of formula known as a structural formula can be required in this scenario. Furthermore, structural formulas can be denoted by a single-dimensional chemical name. However, this type of chemical nomenclature needs multiple terms and words that are not included in the chemical formulas.

Conclusion

The concepts of molecules study material conclude that an atom is the smallest part of a chemical element or a compound. It also states that each molecule is made up of numerous atoms. There is brief information and facts about the structural formulas, molecular size, molecular weight, molecular bonding, characteristics, and the history of the molecules and their concepts in this article.