The key difference between Lewis dot symbol and Lewis structure is that Lewis dot symbol represents electrons in the outermost electron shell of an atom in a molecule whereas Lewis structure represents the structure of molecules using symbols for chemical elements and dot symbols.
Lewis structure is a simple structure which represents the chemical bonds and lone electron pairs in simple molecules. The Lewis dot symbol represents one electron; thus, we need to use two dots to represent a chemical bond.
CONTENTS
1. Overview and Key Difference
2. What is Lewis Dot Symbol
3. What is Lewis Structure
4. Side by Side Comparison – Lewis Dot Symbol vs Lewis Structure in Tabular Form
5. Summary
What is Lewis Dot Symbol?
Lewis dot symbol represents a single electron. Therefore, if we need to show a chemical bond in a molecule, then we need to use two electrons as a pair since a chemical bond forms when two electrons from two different atoms pair with each other. Moreover, we have to use a pair of dots to show a lone electron pair. The dot symbols are placed around the symbol of chemical element to which the particular atom belongs. For example, we can give the electron of the hydrogen atom as follows:
Figure 01: Electron of the Hydrogen Atom
What is Lewis Structure?
Lewis structure is a representation of simple molecules using dot symbols. These dot symbols represent the electrons of the outermost orbital of atoms in the molecule. When drawing a Lewis structure, first we need to find the number of valence electrons of all the atoms in the molecule. Then, we need to find the number of electrons that fill-up the outer electron shell, following the octet rule. After that, we have to determine the number of chemical bonds that are present in the molecule, and we also need to figure out whether they are in single bonds, double bonds and triple bonds.
Moreover, we need to determine a central atom for the molecule depending on the electronegativity of the atoms. Here, the atom having the least electronegativity is taken as the central atom. Then we can draw a skeletal structure for this molecule. For this skeletal representation, we can use the symbols of the chemical elements and dot symbols. We have to use two dots when representing one chemical bond and after placing the electron pairs for the bonds, the remaining electrons can be represented as lone electron pairs.
Let us consider an example in order to understand the methodology of drawing a Lewis structure. The steps for drawing the Lewis structure for the methane molecule is as follows:
Figure 02: Lewis Structure of Methane Molecule
- The chemical formula of methane is CH4.
- The carbon atom is less electronegative than the hydrogen atom. Therefore, the central atom of the molecule is carbon.
- It has four electrons in the outermost electron shell.
- There are four hydrogen atoms around the central carbon atom. Four hydrogen atoms need four electrons from carbon atom to form single chemical bonds. Therefore, all four valence electrons of carbon atoms are involved in bonding, and there are no lone electron pairs around carbon atom in this molecule.
What is the Difference Between Lewis Dot Symbol and Lewis Structure?
Lewis structure is a simple structure that represents the chemical bonds and the lone electron pairs in simple molecules. The key difference between Lewis dot symbol and Lewis structure is that the Lewis dot symbol represents electrons in the outermost electron shell of an atom in a molecule, whereas a Lewis structure represents the structure of molecules using symbols for chemical elements and dot symbols.
Below is a side by side comparison of the difference between Lewis dot symbol and Lewis structure.
Summary – Lewis Dot Symbol vs Lewis Structure
Lewis structure is a simple structure which represents the chemical bonds and the lone electron pairs in simple molecules. The key difference between Lewis dot symbol and Lewis structure is that the Lewis dot symbol represents electrons in the outermost electron shell of an atom in a molecule. Meanwhile, a Lewis structure represents the structure of molecules using symbols for chemical elements and dot symbols
Reference:
1. Helmenstine, Todd. “How to Draw a Lewis Structure.” ThoughtCo, Sep. 6, 2019, Available here.
Image Courtesy:
1. “Hydrogen lewis” By Ricordisamoa – Own work, vector version of File:Hydrogen lewis.png (Public Domain) via Commons Wikimedia
2. “Elektronenformel Punkte CH4” By Apostoloff – Own work (Public Domain) via Commons Wikimedia