# Chemical Graph Theory in Mathematics

*I am a PhD student of mathematics. I have complete MS in math from the University of Pakistan and have been writing online since 2020.*

## Chemical Graph Theory

## Chemical Graph Theory

**Introduction of Graph:**

The study of graphs, which are mathematical constructions used to represent pairwise relationships between things, is known as graph theory in mathematics. Vertices (also known as nodes or points) make up a graph in this sense, which are connected by edges (also called links or lines). It is possible to identify the beginning of graph theory to 1735, when Swiss mathematician Leonhard Euler found a solution to the Konigsberg bridge problem.

Graphs are some of the most practical and common structures used in the modelling of many fields and phenomena in various scientific domains, such as physics and chemistry. Database graphs and computer networking are both of fundamental necessity. In geometry, the terms "point" and "line" indicate a structure 1 with points, where each point has a specific geometric significance and each line's slope is unique.

One requires a better knowledge of graphs in order to assess the various circumstances that might be described by them. In the next sections, the concept of abstract graphs and numerous significant graph theory results will be covered. At the end of this chapter, we will explore and thoroughly go over a few popular graph classes and other outcomes that have some unique importance.

**Graph as Models:**

There are different physical conditions that can be described with the help of diagrams or graphs. A graph is a collection of points and lines, where each point symbolizes an atom and each line acts as a link between those atoms. Finding the gaps in the flow of these networks is our primary goal while dealing with various real-world issues related to computer and communications networks. To fix the problem that is upsetting the graph or drawing, we require the erroneous lines and points for that purpose.

**Chemical Graphs:**

A branch of mathematics known as chemical graph theory combines chemistry and graph theory. Molecules are theoretically modelled using graph theory to reveal the physical characteristics of these chemical substances. Chemical graph theory is a significant area of graph mathematics where various particular and specific types of graphs representing chemical phenomena are examined. Chemical-graph theory, a leading area of study that integrates mathematics and chemistry, includes topology, isomerism, and descriptors.

Graph theory approaches such as combinatorics are used to handle a number of chemistry problems. The theory of chemical graph is a field of mathematical chemistry that studies in-depth analyses of the results of numerous interrelationships. It serves as a useful model for any concrete or fictitious chemical system (molecules or scheme of reaction or transformation in chemicals). In a short, the theory of chemical graphs covers practically all aspects of graph theory's application to chemistry.

The term "chemical" is intentionally used to emphasize the fact that, in contrast to graph theory, chemical graph theory appeals to the basic understanding of many theorems and traditional mathematical proof. Chemical graphs have experienced a paradigm shift and significant growth surge in recent years. For graph theory to become well-known and be used frequently in the field of chemistry, many different things had to come together. Due to its properties, which serve as a model of mathematics for molecules, structural equations of chemical compounds were first the only phenomenon in the natural sciences that came near to the concept of a graph.

**Motivation, Objective and Aim of the Problem:**

Indices or descriptors of molecular composition are used to convey the significance of numerical numbers related to chemical structures. Being a structural invariant, labelling or the illustrated depiction of a graph is not a factor to depend on. This involves a variety of physical qualities, chemical reactivity, or biological processes. Numerous structure descriptors have been gradually offered in studies up to this point, particularly where there is a correlation between various physical attributes, biological processes, and chemical reactions. “23” If a topological index falls within the bounds of steady structural changes, it can provide information about the shape of molecules.

For example, an isomer set index may illustrate a local contribution to a given attribute if it is specified locally. Finally, it may be generated on a variety of bases, such as different matrices, or it might reflect a bigger descriptors group with a long volume to aid regression analysis just in the case of a generic index. Thermodynamic properties showed a strong correlation with the structure in molecular properties. Common examples of thermodynamic properties are combustion, formation enthalpy, and boiling points.

Since the index is based on changes in chemical structure or topology in a single number, it is useful in QSAR and QSPR research. Numerous topological descriptors have been proposed and evaluated up to this point in an effort to establish a relationship between the physical and chemical aspects of QSPR and the biological activity of the molecules involved.

*This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.*

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