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1.1 Explain the occurrence of carboncompounds with straight chains,branched chains and rings.
MODULE 1. THE CHEMISTRY OF
CARBON COMPOUNDS
Learning Outcomes
TOPIC: BONDING IN CARBON
COMPOUNDS
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Carbon forms many more compounds than any otherelement. This is partly because, once formed, thecarbon to carbon (C- C) single covalent bonds are
very strong in comparison to other single covalent
bonds. It takes a lot of energy to break these strong bonds, so
the compounds form are stable.
The ability of carbon atoms to form chains or rings
compounds by joining together is calledCATENATION.
Carbon-carbon bonds are also non-polar, and this
helps to reduce their vulnerability by other chemicals.
BONDING IN CARBON COMPOUNDS
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Carbon atom:
is tetravalent
has the ability to bond with other carbon
atoms to form straight chains, branches andring compounds. This is known as catenation.
has the ability to mix and rearrange the four
orbitals in the outer shell (hybridization) e.g.
sp3, sp2, sp.
has resonance (delocalized electrons)
WHY CARBON IS THE UNIQUE THAT IT
FORMS A LARGE VARIETY OF COMPOUNDS?
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Carbon atoms are able to form a few types of
covalent bonds with other carbon atoms or atoms ofother elements:
Single bonds: C-C, C-H, C-O, C-X
(X = halogens)
Double bonds: C=C, C=O
Triple bonds: C C, CN
Organic compounds can be classified as
unbranched, branched or ring compounds.
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Straight-chain moleculesthat are unbranched maycontain single, double ortriple bonds. E.g.:
Straight (unbranched) Chain Compounds
Single bond Double bonds
Triple bonds
Branched- Chain Compounds
Branched chain compounds
consist of one or morecarbons of a straight chaincompound forming bonds
with more than two
carbons.
http://www.google.com/url?sa=i&rct=j&q=branched+and+straight+chain&source=images&cd=&cad=rja&docid=M9hyEuuYlP0_rM&tbnid=vfPl-U4E1ILDjM:&ved=0CAUQjRw&url=http%3A%2F%2Fwww.gcsescience.com%2Fo24.htm&ei=71qSUZO4EYaQ9gTQ44HgAw&bvm=bv.46471029,d.dmQ&psig=AFQjCNHqJmmMrwbeeXNvb7i5Z1d_RxjyHg&ust=1368631854216888http://www.google.com/url?sa=i&rct=j&q=branched+and+straight+chain&source=images&cd=&cad=rja&docid=M9hyEuuYlP0_rM&tbnid=vfPl-U4E1ILDjM:&ved=0CAUQjRw&url=http%3A%2F%2Fwww.gcsescience.com%2Fo24.htm&ei=71qSUZO4EYaQ9gTQ44HgAw&bvm=bv.46471029,d.dmQ&psig=AFQjCNHqJmmMrwbeeXNvb7i5Z1d_RxjyHg&ust=1368631854216888http://www.google.com/url?sa=i&rct=j&q=branched+and+straight+chain&source=images&cd=&cad=rja&docid=M9hyEuuYlP0_rM&tbnid=1LBgrNmTKwxHgM:&ved=&url=http%3A%2F%2Fwww.gcsescience.com%2Fo24.htm&ei=rViSUeKPLcbo0wHU2YD4Bg&bvm=bv.46471029,d.dmQ&psig=AFQjCNHqJmmMrwbeeXNvb7i5Z1d_RxjyHg&ust=13686318542168887/27/2019 01(1.1)Bonding in Carbon Compounds
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Ring Chain Compounds
Ring chain compounds consist of a ring of carbonatoms
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A covalent bond is formed by sharing of twoelectrons, one from each atom. Carbon can formfour bonds because one of the 2s electrons in thecarbon atom is transferred to a 2p orbital to give
the four unpaired electrons necessary for formingfour bonds.
The process of mixing atomic orbitals is calledHYBRIDIZATION
Hybridisation in Carbon Compounds
http://www.google.com/url?sa=i&rct=j&q=sp3+hybridization&source=images&cd=&cad=rja&docid=dvYY9vNWn7AD5M&tbnid=Y4UJ9w8519aznM:&ved=0CAUQjRw&url=http%3A%2F%2Fchemwiki.ucdavis.edu%2FOrganic_Chemistry%2FFundamentals%2FHybrid_Orbitals&ei=_l2SUf-8HIyi8gSb7YHgDw&bvm=bv.46471029,d.dmQ&psig=AFQjCNFFvuSpDnDh5CXhoAr2TUSp7hB4NA&ust=1368633204297691http://www.google.com/url?sa=i&rct=j&q=sp3+hybridization&source=images&cd=&cad=rja&docid=dvYY9vNWn7AD5M&tbnid=Y4UJ9w8519aznM:&ved=0CAUQjRw&url=http%3A%2F%2Fchemwiki.ucdavis.edu%2FOrganic_Chemistry%2FFundamentals%2FHybrid_Orbitals&ei=_l2SUf-8HIyi8gSb7YHgDw&bvm=bv.46471029,d.dmQ&psig=AFQjCNFFvuSpDnDh5CXhoAr2TUSp7hB4NA&ust=13686332042976917/27/2019 01(1.1)Bonding in Carbon Compounds
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Hybridisation in Carbon Compounds
http://www.google.com/url?sa=i&rct=j&q=ethane+sp3+hybridization&source=images&cd=&cad=rja&docid=BcgAe4JAqyIt0M&tbnid=TKvYdM0KBf1dKM:&ved=0CAUQjRw&url=http%3A%2F%2Fwww.jagemann-net.de%2Forbital%2Forbitale.php&ei=F2iSUf3LG4_s8gStq4DgCw&bvm=bv.46471029,d.dmQ&psig=AFQjCNGaZvbF5lF4Fl0LtZTZQV2cp7efWw&ust=1368635779940587http://www.google.com/url?sa=i&rct=j&q=sp3+hybridization&source=images&cd=&docid=LoRmirJR8eQKuM&tbnid=t22BvvPjPnT6RM:&ved=0CAUQjRw&url=http%3A%2F%2Fchemistry.tutorvista.com%2Forganic-chemistry%2Fvalence-bond-theory.html&ei=fmaSUeuxOYq48wSb2YGQBg&bvm=bv.46471029,d.dmQ&psig=AFQjCNFFvuSpDnDh5CXhoAr2TUSp7hB4NA&ust=1368633204297691http://www.google.com/url?sa=i&rct=j&q=sp3+hybridization&source=images&cd=&docid=LoRmirJR8eQKuM&tbnid=t22BvvPjPnT6RM:&ved=0CAUQjRw&url=http%3A%2F%2Fchemistry.tutorvista.com%2Forganic-chemistry%2Fvalence-bond-theory.html&ei=fmaSUeuxOYq48wSb2YGQBg&bvm=bv.46471029,d.dmQ&psig=AFQjCNFFvuSpDnDh5CXhoAr2TUSp7hB4NA&ust=13686332042976917/27/2019 01(1.1)Bonding in Carbon Compounds
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Hybridisation in Carbon Compounds
http://www.google.com/url?sa=i&rct=j&q=sp2+hybridization&source=images&cd=&cad=rja&docid=KZ8fiaUU5yJ1IM&tbnid=hkotK3l0HMDP1M:&ved=0CAUQjRw&url=http%3A%2F%2Facphsorgo.wikia.com%2Fwiki%2FAlkenes%3A_Structural_Characteristics&ei=p2eSUeL9OZO89gTOgoC4BA&bvm=bv.46471029,d.dmQ&psig=AFQjCNEvHEpsOpn51qHABh7konKC1Y9Ksw&ust=1368635622484318http://chemwiki.ucdavis.edu/Organic_Chemistry/Organic_Chemistry_With_a_Biological_Emphasis/Chapter__1%3A_Chapter_1%3A_Introduction_to_organic_structure_and_bonding_I/Section_1.5%3A_Valence_bond_theory%3A_sp,_sp2,_and_sp3_hybrid_orbitalshttp://chemwiki.ucdavis.edu/Organic_Chemistry/Organic_Chemistry_With_a_Biological_Emphasis/Chapter__1%3A_Chapter_1%3A_Introduction_to_organic_structure_and_bonding_I/Section_1.5%3A_Valence_bond_theory%3A_sp,_sp2,_and_sp3_hybrid_orbitals7/27/2019 01(1.1)Bonding in Carbon Compounds
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Resonance
In ethane and ethene the electrons are localised. Insome substances, the molecular orbitals extendover three or more atoms, allowing the electronsfree movement over these atoms. These electrons
are said to be delocalised. Benzene (C6H6) has 6 carbon atoms arranged in a
ring. The bonds between the carbon atoms areneither double nor single bonds. They are
somewhere in between. Making up a compositestructure from several different structures is calledmesomerism. The composite structure is called aresonance hybrid.
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Resonance
Resonance arises whenever we can write two or morestructures for a molecule with different arrangementsof the electrons but identical arrangements of atoms.
When resonance is possible, the substance that is aresonance is said to have a structure that is a resonance
hybrid of the various contributing structures.
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Resonance in Benzene
Compounds such as benzene, which have this
delocalised electron ring structure are called arylcom ounds.
http://www.google.com/url?sa=i&rct=j&q=resonance+in+benzene&source=images&cd=&cad=rja&docid=Dg5YKqSabkGd_M&tbnid=jjzsBjUtjJ3aiM:&ved=0CAUQjRw&url=http%3A%2F%2Forganickmetz.blogspot.com%2F2011%2F02%2Faromaticity-description-for-non-science.html&ei=5WqSUeLdLI7M9gTI64CoCw&psig=AFQjCNFuKT4DOnUChtYZu6_zgD5InJOtNw&ust=1368636380763394http://localhost/var/www/apps/conversion/tmp/scratch_8//upload.wikimedia.org/wikipedia/commons/0/03/Benzene_resonance_structures.pnghttp://localhost/var/www/apps/conversion/tmp/scratch_8//upload.wikimedia.org/wikipedia/commons/0/03/Benzene_resonance_structures.png7/27/2019 01(1.1)Bonding in Carbon Compounds
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Key Points
A large number of carbon compounds are formed bycatenation- the joining of carbon atoms together toform straight or branched chains of atoms or ringcompounds.
Most organic compounds are stable because of thehigh value of the C-C bond energy and the non-polarnature of this bond.
Hybridisation of s and p orbitals results in theformation of an orbital with mixed character.
Resonance is where the structure of a compound is asingle form which is in-between two or more
structures.
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Explain the characteristic of compounds
which belongs to the same homologous
series.
Homework
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