# 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 $\mathrm{Y}$ .

how environment affect demand and supply of commodity ?
Wht at the criteria for market ?
Amos
what is difference between monitory policy and fiscal policy?
monetary policy is a policy thrust by National Govt(CBN) to influence government spending, purchase &taxes
Frank
necessity of economics
I will say want,choice,opportunity cost,scarcity,scale of preference
Alao
what is monopoly market.How price output are determined under monopoly market
bisham
b) Monopoly market is an impecfect market where s single firm having the innovation to produce a particular commodity.Prices are determined through output since there are no other competitive.
Frank
Monopoly market:firm has market power & does not respond to market price
Frank
Explain the process of price determination under perfect competition market with suitable diagram
Price determination under perfect competition via this process :firms have no market power to influence price rather firms respond to market price.
Frank
price is different from demand- demand is amount of commodity
demand is amount /quantity of commodity a potential buyer is willing to buy at a given price at market
Frank
demand is a desire of customer on commodity with the ability to pay it and willing to buy it at given price of commodity
Harika
demand is price of what
show that shortrun average cost
what is economics
what is money
Mbah
what is money
Mbah
Difine macro economics
agaba
money is a medium of exchange between goods and services,maybe inform of currency.
Wesonga
Economics is study of how human beings strive to satisfy numerous wants using limited available resources.
Wesonga
how do you find the maximum number of workers the firms should employ order to produce where there are increasing returns
Jane
what are implications of computing national income?.
agaba
pl
MUDASIRU
what is the formulae for calculating national income
MUDASIRU
it calculated by value added method
Praveen
classify the production units like agriculture, banking, transport etc
Praveen
money is anything that is generally acceptetable for human
Ogbaji
Estimate the net value added(NVA) at fixed cost by each industrial structure
Praveen
definition of unemployment
what are the causes of unemployment?
The main causes of unemployment are listed below. 1. Frictional unemployment 2. Cyclical unemployment 3. Structural unemployment
assani
We can also categorize the causes on a broader sense as: 1. Political and 2. Social cause As unemployeement root causes are embaded in this two.
Yonathan
would opportunity cost exist if there was no scarcity?
assani
yes just because the opportunity cost arose when there is Alternative to choose among the alternatives.
I am thinking that, if our resources were unlimited, then there wouldn't be any need to forgo some wants. Hence the inexistence if opportunity cost
assani
Politics
Job
politics has done what?
assani
consider time assani
Mary
I'm Emmanuel,...I taught the main cause is the change in gov't.
Emmanuel
...Lack of capital to set up a firm respectively
Emmanuel
🙈
Emmanuel
I would like to bring in Educational levels can also be the cause the cause of the problem respectively
Emmanuel
I think the main causes of unemployment is lack of INFRASTRUCTURAL DEVELOPMENT OVER POPULATION OVER DEPENDENT ON GOVERNMENT LACK OF SELF EMPOWERMENT...
ananti
lack of skills among the new generation is the serious issue.
Vishal
Where I come from , I don't see why education or personal aspects seem to do with unimployment, technically the motivation and eigerness in all works of live is there , dispite the cultural influence and physical bearriors;the thing we lacking is Government Support and open market ethics.
Joe
sorry about that-(repation). We have a over powering ethical political system that's displacing the marketing asspects of economy and causing large scale unemployment right across the board...
Joe
can someone Explain Expansionary Monetary Policy and Contractionary Monetary Policy Using one of the instrument of Monetary Policy? Please am kinda lost here?. ta
using a graph show the case of substitute and compliment goods
can anyone give me a simple explanation to Five Sector Macroeconomics?
Emmanuel
Can someone please define what economics is
economics simply is a social science subject that study human behavior.
dajan
economics is a social science which studies human behaviour as a relationship between ends and scarce means that has alternative uses
Alao
Can someone please tell me how to calculate GDP
Emmanuel
emmanual kapal to calculate GDP (Gross Domestic Product) has three method in calculating it (1)income approach (2) expenditure approach (3) value added method
Alao
thanks Alae
Emmanuel
u are welcome
Alao
in basic terms economics is revered to as battery system, it date back to when Men sees the need to exchange sapless goods and produce to gain , either wealth , basic necessities or to establish trading ties for personal benefit or social asspects in terms of coexistence and continuity, future .
Joe
what is the law of demand
keep other thing constant, when the price increases demand decrease when the price decreases demand increases of the commodity.
sj
all things being equal,quantity demanded decrease as price increase and increase as price decrease
Seth
there's practial joke to it ..." the higher the demand ; scarcity, increase in production and drop in quality"... quite the controversy - for example China vs Europe, United States and we are all boxed up in between somewhere...
Joe
Other thing remain constant the low price of commodity the high quantity of commodity and vice versa is true
Baraka
Explain Effective demand
What is effective demand
Anita
like Modi is in demand...best example of effective demand
Pranav
Don't get you
Anita
Anita you mean you don't get me or who?
Onyeking
level of demand that represents a real intention to purchase by people with the means to pay
Pranav
Difference between extinct and extici spicies
While the American heart association suggests that meditation might be used in conjunction with more traditional treatments as a way to manage hypertension
Researchers demonstrated that the hippocampus functions in memory processing by creating lesions in the hippocampi of rats, which resulted in ________.
The formulation of new memories is sometimes called ________, and the process of bringing up old memories is called ________.
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