THE 7 MOST IMPORTANT CONTRIBUTIONS OF LEWIS AND PAULING - CHEMISTRY - 2024

The contributions of Lewis and Pauling revolutionized the modern scientific field, their investigations in the physicochemical areas were and are of vital importance in different branches of chemistry and biology.

Linus Pauling is a physicist and chemist from the United States of America whose name became known for his research on chemical bonding and molecular structures.

Linus pauling

He was a student at the University of Oregon, a region in which he developed most of his theories and foundations. His research began to bear fruit around 1930 while he was a professor of chemistry at the University of Oregon.

From 1927 to 1964 he managed to create the current bases of molecular study, reducing chemistry to physics. His book "The nature of the chemical bond" is the book with the most references cited by the scientific community and one of the most important publications in contemporary scientific history.

Gilbert Newton Lewis, born much earlier, carried out important studies on the peripheral electrons of atoms among other contributions of great importance that will be named below.

Gilbert Newton Lewis

His work as professor of physicochemistry and dean at the University of California was definitely fruitful.

Linus Pauling and Gilbert Lewis, both scientists and professors, were instrumental in the development and understanding of new research methods.

The first enhanced current research on the nature of chemical bonds and the latter evidenced the nature of nucleons and the officialization of thermodynamic chemistry.

Gilbert Lewis contributions

The cubic atom

The Lewis atomic model is considered a previous version of the current atomic model, whose valence electrons are located within a hypothetical cube used as a referent to represent the atomic structure.

This model was useful to also formalize the concept of valence, which would be nothing more and nothing less than the ability of an atom to combine to form a compound.

The octet rule

It was in 1916 when Gilbert Newton Lewis announced that the atoms of the periodic system tend to obtain their last energy levels with 8 electrons, so that their configuration is stabilized, even equaling a noble gas.

This rule is applicable in the bonding of atoms that will determine the nature, behavior and attributes of the molecules.

Heavy water

In 1933, by electrolysis, the first sample of heavy water was separated in its pure state, deuterium oxide, an isotope of hydrogen instead of an isotope of hydrogen-1 or protium, which makes it 11% denser than water. light.

Lewis structure

It is the molecular structure in which the valence electrons are symbolized as points between the atoms that make a bond.

In other words, two points signify a covalent bond, a double bond would then become two pairs of points, among others.

Electrons are also symbolized as points but are placed adjacent to atoms. These are the following formal charges (+, -, 2+, etc.) that are added to the atoms to differentiate between the positive nuclear charge and all the electrons.

Pauling contributions

Electronegativity

Electronegativity studies the tendency of an atom to attract a cloud of electrons while an atomic bond occurs.

It is used to order elements according to their electronegativity and was developed in 1932 leading this method to future discoveries and advances in current chemistry.

The measurements are pragmatic traits ranging from 4.0 to the highest (fluorine) and a range of 0.7 to francium, all other ranges oscillating between these two denominations.

The nature of the chemical bond and the structure of crystal molecules

It is the book most cited by scientists since its publication in 1939, catapulting Pauling to the fore in the scientific community of yesterday and today.

It was Pauling who proposed the theory of hybridization as a mechanism that justifies the distribution of valence electrons, be they tetrahedral, flat, linear or triangular.

A hybrid orbital are combined atomic orbitals. Hybrid orbitals have an equal shape and a fair spatial orientation.

The number of hybrid orbitals formed is equivalent to the number of atomic orbitals that are combined, they also have a binding zone or lobe.

Discovery of the alpha helix and beta sheet

For the explanation of the alpha helix, Pauling argues that the structure consisted of a three-stranded helix, with the sugar-phosphate chain in the center.

However, the data was empirical and there were still a number of flaws to correct. It was then that Watson and Crick showed the world the current double helix that defines the structure of DNA.

Rosalind Franklin had obtained a visual sample of the helical base of DNA and it was named Structure B. Her crystallographic work was essential to this find.

The beta sheet or folded sheet was another of the models proposed by Pauling in which he explains the possible structures that a protein is able to adopt.

It is formed by the parallel positioning of two amino acid chains in the same protein, this model was shown in 1951 by Pauling together with Robert Corey.

Serology

The field of serology was also dominated by Pauling who then turned his mind to the interaction and dynamism between antigens and antibodies.

He even managed the theory that the reason antigens and antibodies could be specifically combined was because of their affinity in the shape of their molecules.

This theory was called the theory of molecular complementarity and created a wide array of later experiments that, in reinforcement of this theory, would lead him down new paths in the serological field.