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Octet Rule: For elements in Groups 4 through 8 in Periods 2 and 3 of the Periodic Table, the valence of each atom plus the number of valence electrons in each atom is equal to 8.

Observation 2: covalent bonding

As a way to think about this pattern, remember that for each of the atoms in these two periods, the valence shell can accommodate eight electrons. It turns out that the valence of each atom in Groups 4 through 8 is equal to 8 minus the number of valence electrons the atom has. For example, the valence of an N atom is 3, which is equal to 8 minus the number of valence electrons in N, which is 5. This tells us that, for each of these atoms, the number of bonds the atom typically forms is equal to the number of vacancies in its valence shell.

This suggests a model which would account for the Octet Rule. It appears that each atom in these Groups attempts to bond to other atoms so as to completely fill its valence shell with electrons. For elements in Groups 4 through 8, this means that each atom attempts to complete an “octet” of valence shell electrons. (Why atoms should behave this way is a question unanswered by this model.)

Consider, for example, the combination of two chlorine atoms to form Cl 2 . Each chlorine atom has seven valence electrons and seeks to add a single electron to complete an octet. Hence, chlorine has a valence of 1. Either chlorine atom could satisfy its valence by “taking” an electron from the other atom, but this would leave the other atom now needing two electrons to complete its valence shell. The only way for both atoms to complete their valence shells simultaneously is to share two electrons. Each atom donates a single electron to a shared electron pair. This sharing of electrons is what we call a chemical bond. More specifically, we call this a “covalent bond,” so named because the bond acts to satisfy the valence of both atoms. The two atoms are thus held together by the need to share the electron pair.

Let’s apply this to a molecule with an H atom, HCl. H atoms are not expected to have an octet. In fact, the valence shell in H can accommodate just two electrons. Because an H atom has 1 valence electron, it thus has a single vacancy, or a valence of 1. Our model for electron pair sharing works for H atoms as well. When H and Cl bond, they share a pair of electrons forming a covalent bond so that the H atom has a full valence shell (two electrons) and the Cl atom has a full valence shell (eight electrons).

We now have two important pieces of our model. First, atoms form a covalent bond by sharing a pair of electrons. Second, for atoms in Groups 4 through 8, they tend to share enough electrons to fill the valence shell with 8 electrons, and this determines the number of covalent bonds they form. An H atom shares one pair of electrons to form a single covalent bond.

Observation 3: molecular structures in compounds of carbon and hydrogen

Many of the most important chemical fuels are compounds composed entirely of carbon and hydrogen, i.e. hydrocarbons. The smallest of these is methane CH 4 , a primary component of household natural gas. Other simple common fuels include ethane C 2 H 6 , propane C 3 H 8 , butane C 4 H 10 , pentane C 5 H 12 , hexane C 6 H 14 , heptane C 7 H 16 , and octane C 8 H 18 .

Questions & Answers

an increase in demand (while supply remains constant) what will happen to deh graph?
Thabiso Reply
what is going to happen to the graph if there is an increase in demand, While supply remains constant .
Thabiso
What will happen to the graph if there is an increase in demand While supply remains constant?
Thabiso
price will increase high than automatically demand will decrease
takshaveer
equilibrium ?
Issum
what is demand
Sarkwah Reply
demand is the willingness to buy a commodity backed by the ability to pay.
Runwell
demand is mere desire on commodity with ability to back up with purchasing power
Terkimbi
Equilibrium is when there's an equality between quantity demanded and quantity supplied
Victory Reply
Again the consumer will be in equilibrium if the price of the commodity is equal to Marginal utility of that product
daniel
wat is the law of supply
Agnes Reply
It's what* -The law of supply states that price and supply is relative. As all factors are equal, if price increases then quantity of supply there for increases.
Nathaniel
the law of suppy state that when prise is high, more commodity with be supply and when p is low less of the same commodity will be supply.
BEGE
It states that, "other things being equal, move supplied at a higher price than at a lower price ".
Murewah
okay
Agnes
it's state that the increased in prices will lead to decreased in supply
Asuquo
what is the theory of supply and the determinants of demand
Murewah
And please what is change in quantity supplied?
Agnes
guys why are you so quiet
Murewah
A woman has a television set which cost her $800 two years ago. A new set would cost her $1000 and she could sell her television set for $450. What is the opportunity Cost of keeping the old TV?
Murewah Reply
principle of effective demand?
Abubakar Reply
the is the situation in which the need of individuals exceed the available resource. increase in population rate and wrong decision making
esther Reply
what is the different between wants and demand?
Terkimbi
wants are what people desire to have but they can live without them and demand is a thing that is most wanted
Murewah
what are the demand pull inflation
Hijja
the higher the aggregate level of activity, the larger the proportion of areas and industries which experience excess demand for goods and labour of various sorts , and the more powerful is demand-inflationary pressure . Demand inflation is contrasted with cost inflation , in which price and wage
Murewah
increases are transmitted from one sector to another. These should be regarded as different aspects of an overal inflation starts , cost inflation explains why inflation once begun is so difficult to stop.
Murewah
what is the important difference between positive and normative economics
Umar
positive economics is the study of how an economy works in practice, as opposed to the theoretical study of how it should run in theory and normative economics is the party of economics that is concerned with how the economy ought to be run.
Murewah
positive economic deal with fact and also talks about how the economy actually is like while normative economic deal with value judgement and talks about how the economy ought to be like
esther
What is the difference between opportunity cost and choice
Murewah
opportunity cost are also known as forgun alternative why choice is to select one among alternative
Terkimbi
importance of economic
Zakaria Reply
satisfaction of human wants
Festo
economics is about to economise . discuss
Angel Reply
Underlines the efficiency aspect. Economise towards what: Economise factors to reach equal distribution of Material wealth or Just to operate optimally to Service demand, i. e. Run markets efficiently?
Homo
join the conversation
abba Reply
Hi I'm Ashnly Parker.
Murewah
what is terms of trade
Ibrahim Reply
different btn import and export
Angel
No question... This is nice
Gbenga Reply
hw can we solve problem of scarcity
Oigebe
scarcity is not necessarily a problem but a constant condition of the world. there are not enough resources to satisfy the unlimited wants.
Matthew
wee need to be cooperative
Zakaria
by unlimited resourses and abundant want
Angel
What is the economic problem
Murewah
inflation
Lazizjon
And what is demand pull inflation
Murewah
why do compute GDP?
steven Reply
can anyone shortly determine the word inflation.
Ibrahim Reply
Continous increase in the general level of prices or in the cost of living.
arshad
persistent increased in general price level
Machall
all correct...
paa
inflaction
Angel
rise in price.
Abubakar
deserving of money
Lazizjon
A persistent tendency for nominal prices to increase
Murewah
What is the problem of economic problem
Murewah
the father of economics
Reuben Reply
Adem smith
sj
Adem smith
Ajit
Adem smith sure
Adigwe
the father of economic regarding to adam Smith
Ibrahim
the father of political of economic and capitalism in his book and inquary in to the wealth of the nation.
Umar
Adam Smith his the father of economic
Mamudu
difference between injection and leakage
Asif
what is monopoly
Razak
Monopoly is a market structure where there is one firm who dominate the industry
wisdom
hi,, I am new here. please welcome me.
Mohammad
you are welcome
Adigwe
monopoly is the one characterized by a mkt power in which a firm is a price maker
Festo
Some member just ask questions but not answering so y this happen
Festo
Monopoly is a market where only one seller exists. No competition
Fred
how long does the patent right prevail the monopoly
Festo
no attempt
Zakaria
what is state farming
Sadiq
anybody to attempt
Festo
Hi, I'm a new member please will you welcome me
Murewah
A soccer field is a rectangle 130 meters wide and 110 meters long. The coach asks players to run from one corner to the other corner diagonally across. What is that distance, to the nearest tenths place.
Kimberly Reply
Jeannette has $5 and $10 bills in her wallet. The number of fives is three more than six times the number of tens. Let t represent the number of tens. Write an expression for the number of fives.
August Reply
What is the expressiin for seven less than four times the number of nickels
Leonardo Reply
How do i figure this problem out.
how do you translate this in Algebraic Expressions
linda Reply
why surface tension is zero at critical temperature
Shanjida
I think if critical temperature denote high temperature then a liquid stats boils that time the water stats to evaporate so some moles of h2o to up and due to high temp the bonding break they have low density so it can be a reason
s.
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
Crystal Reply
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
Chris Reply
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Source:  OpenStax, Concept development studies in chemistry 2013. OpenStax CNX. Oct 07, 2013 Download for free at http://legacy.cnx.org/content/col11579/1.1
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