Do you have to use the Lewis spelling in chemistry right now, but don’t know exactly how to do it? Then you are exactly right here. Everything is explained to you here in a way that is easy to understand. The topic is part of the periodic table subtopic.
What is the Lewis spelling?
Both atoms and molecules can be represented in different ways. One way of representing them is with the so-called Lewis notation. She will too Lewis formula or electron formula called. You can use the Lewis formula to represent the structure of atoms and molecules.
Based on the octet rule and the different types of chemical bonds, you can also use Lewis notation to represent the bonds between atoms. According to the Lewis notation, only the valence electrons are involved in a bond.
In short: With the Lewis notation you can represent atomic bonds in atoms and molecules more easily
How is Lewis spelling used?
When using Lewis spelling, you need to know that only the Electrons of the highest energy level of an atom, also called valence electrons. This means that the inner electrons and the actual structure of the atomic nucleus have no influence.
The Lewis formula consists of the element symbol and the respective valence electrons. You can easily read how many valence electrons an atom has from the periodic table of the respective main group.
A valence electron is represented as a dot, while in the valence line formula the bonds are only drawn as dots and are not connected to form a line.
Important! Difference to the valence bond formula: In the Lewis formula, the electrons are represented as dots. In the valence line formula, two points are shown connected to form a valence line.
In short:
- Only the valence electrons are taken into account
- A valence electron is represented as a dot
Lewis spelling using the example: hydrogen (H₂)
A hydrogen atom has only one valence electron, while the hydrogen molecule is diatomic and therefore attains an inert gas configuration in the molecular compound. The closest one is that of helium, since a helium atom has two valence electrons.
So we now have two hydrogen atoms, each with one electron, which achieve the stable electron configuration of helium with two valence electrons, since this state is energetically favored and therefore very stable.
Hydrogen atoms with their valence electrons
In Lewis notation, this is in the form of
H・H
shown. So you first write down the symbol of the element from the periodic table and then a dot for each valence electron.
hydrogen molecule
With the Lewis formula, one would define the hydrogen molecule as
H・・H (American spelling)
represent.
But what if an atom has more than one valence electron? The solution is very simple: Points are placed around the element symbol according to the number of outer electrons. We have an example of this in the next paragraph.
Lewis spelling using the example: carbon dioxide (CO₂)
There are two oxygen atoms each having six valence electrons and there is one carbon atom with four valence electrons. Again, you have to pay attention to the octet rule and the molecular bond.
Carbon and two oxygen atoms with their valence electrons
Using Lewis notation, carbon dioxide looks like this:
carbon dioxide molecule
Since a dot represents an electron, using Lewis notation you get:
Source: pngwing.com
In the valence bond formula, you could connect two electrons, i.e. a pair of electrons, to form dashes.
Lewis spelling – Everything important at a glance
- Lewis notation is used for the simple representation of atoms and molecules.
- Only the valence electrons are shown.
- A valence electron is a point.
- The dots are painted around the element symbol.
- In the valence bond formula, two points can be connected to form a line.