# 5.1 Lewis structures

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## Lewis notation and molecular structure

Although we have used diagrams to show the structure of molecules, there are other forms of notation that can be used, such as Lewis notation and Couper notation . Lewis notation uses dots and crosses to represent the valence electrons on different atoms. The chemical symbol of the element is used to represent the nucleus and the core electrons of the atom.

So, for example, a hydrogen atom would be represented like this:

A chlorine atom would look like this:

A molecule of hydrogen chloride would be shown like this:

The dot and cross in between the two atoms, represent the pair of electrons that are shared in the covalent bond.

Represent the molecule $\mathrm{H}{}_{2}\mathrm{O}$ using Lewis notation

1. The electron configuration of hydrogen is $1\mathrm{s}{}^{1}$ and the electron configuration for oxygen is $1\mathrm{s}{}^{2}2\mathrm{s}{}^{2}2\mathrm{p}{}^{4}$ . Each hydrogen atom has one valence electron, which is unpaired, and the oxygen atom has six valence electrons with two unpaired.

2. The water molecule is represented below.

Represent the molecule $\mathrm{HCN}$ (hydrogen cyanide) using Lewis notation

1. The electron configuration of hydrogen is $1\mathrm{s}{}^{1}$ , the electron configuration of nitrogen is $1\mathrm{s}{}^{2}2\mathrm{s}{}^{2}2\mathrm{p}{}^{3}$ and for carbon is $1\mathrm{s}{}^{2}2\mathrm{s}{}^{2}2\mathrm{p}{}^{2}$ . This means that hydrogen has one valence electron which is unpaired, carbon has four valence electrons, all of which are unpaired, and nitrogen has five valence electrons, three of which are unpaired.

2. The $\mathrm{HCN}$ molecule is represented below. Notice the three electron pairs between the nitrogen and carbon atom. Because these three covalent bonds are between the same two atoms, this is a triple bond.

Represent the molecule $\mathrm{H}{}_{2}\mathrm{S}$ (hydrogen sulphide) using Lewis notation

1. Hydrogen has an electron configuration of $1\mathrm{s}{}^{1}$ and sulphur has an electron configuration of $1\mathrm{s}{}^{2}2\mathrm{s}{}^{2}2{p}{}^{6}3\mathrm{s}{}^{2}3\mathrm{p}{}^{4}$ . Each hydrogen atom has one valence electron which is unpaired, and sulphur has six valence electrons. Although sulphur has a variable valency, we know that the sulphur will be able to form 2 bonds with the hydrogen atoms. In this case, the valency of sulphur must be two.

2. The $\mathrm{H}{}_{2}\mathrm{S}$ molecule is represented below.

Another way of representing molecules is using Couper notation . In this case, only the electrons that are involved in the bond between the atoms are shown. A line is used for each covalent bond. Using Couper notation, a molecule of water and a molecule of $\mathrm{HCN}$ would be represented as shown in figures [link] and [link] below.

## Atomic bonding and lewis notation

1. Represent each of the following atoms using Lewis notation:
1. beryllium
2. calcium
3. lithium
2. Represent each of the following molecules using Lewis notation:
1. bromine gas ( $\mathrm{Br}{}_{2}$ )
2. carbon dioxide ( $\mathrm{CO}{}_{2}$ )
3. Which of the two molecules listed above contains a double bond?
4. Two chemical reactions are described below.
• nitrogen and hydrogen react to form $\mathrm{NH}{}_{3}$
• carbon and hydrogen bond to form a molecule of $\mathrm{CH}{}_{4}$
For each reaction, give:
1. the valency of each of the atoms involved in the reaction
2. the Lewis structure of the product that is formed
3. the chemical formula of the product
4. the name of the product
5. A chemical compound has the following Lewis notation:
1. How many valence electrons does element $\mathrm{Y}$ have?
2. What is the valency of element $\mathrm{Y}$ ?
3. What is the valency of element $\mathrm{X}$ ?
4. How many covalent bonds are in the molecule?
5. Suggest a name for the elements $\mathrm{X}$ and $\mathrm{Y}$ .

where we get a research paper on Nano chemistry....?
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
what are the products of Nano chemistry?
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
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da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
ya I also want to know the raman spectra
Bhagvanji
I only see partial conversation and what's the question here!
what about nanotechnology for water purification
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
why we need to study biomolecules, molecular biology in nanotechnology?
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
why?
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
how did you get the value of 2000N.What calculations are needed to arrive at it
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Good
The fundamental frequency of a sonometer wire streached by a load of relative density 's'are n¹ and n² when the load is in air and completly immersed in water respectively then the lation n²/na is
Properties of longitudinal waves