Bonding in Carbon Compounds PDF

What Do These Compounds Have in Common? How is one element able to form such a variety of compounds?  Think Time? - write the formula of three organic compounds studied in 5th Form - identify the number of bonds of each carbon atom - explain the numb...

What Do These Compounds Have in Common? How is one element able to form such a variety of compounds?  Think Time? - write the formula of three organic compounds studied in 5th Form - identify the number of bonds of each carbon atom - explain the number of bonds according with the atomic structure of carbon atom MODULE 1. THE CHEMISTRY OF CARBON COMPOUNDS TOPIC: BONDING IN CARBON COMPOUNDS Learning Outcomes 1.1 Explain the occurrence of carbon compounds with straight chains, branched chains and rings. BONDING IN CARBON COMPOUNDS  Carbon forms many more compounds than any other element. This is partly because, once formed, the carbon 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 called CATENATION.  Carbon-carbon bonds are also non-polar, and this helps to reduce their vulnerability by other chemicals.  WHY CARBON IS THE UNIQUE THAT IT FORMS A LARGE VARIETY OF COMPOUNDS? Carbon atom: ▪ is tetravalent ▪ has the ability to bond with other (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)  Hybridisation in Carbon Compounds There are five types of formulae which can be used to describe and identify organic compounds:  Carbon is in Group IV of the Periodic Table. This means that it has 4 electrons in its outer principle quantum shell., which are able to form bonds with other atoms. It exhibits TETRAVALENCY. ttp://en.citizendium.org/images/thumb/3/32/Carbon_electron_configuration.JPG/600px-Carbon_electron_configuration.JPG  Hybridisation in Carbon Compounds  A covalent bond is formed by sharing of two electrons, one from each atom. Carbon can form four bonds because one of the 2s electrons in the carbon atom is transferred to a 2p orbital to give the four unpaired electrons necessary for forming four bonds.  The process of mixing atomic orbitals is called HYBRIDASATION http://t1.gstatic.com/images?q=tbn:ANd9GcQXH7erfCHtCubVeIQSBu1MHRTeGPGckxzQhkRA--VKVMICnj3y http://t1.gstatic.com/images?q=tbn:ANd9GcQXH7erfCHtCubVeIQSBu1MHRTeGPGckxzQhkRA--VKVMICnj3y  Hybridisation in Carbon Compounds http://images.tutorvista.com/content/chemical-bonding/sp3--hybridisation-representation.gif http://images.tutorvista.com/content/chemical-bonding/sp3--hybridisation-representation.gif http://www.jagemann-net.de/orbital/files/ethan_orbitale-2.png  Hybridisation in Carbon Compounds http://chemwiki.ucdavis.edu/@api/deki/files/8678/=image192.png http://chemwiki.ucdavis.edu/@api/deki/files/8678/=image192.png http://images2.wikia.nocookie.net/__cb20101202193044/acphsorgo/images/5/5f/EthyleneOrbitals.gif  Resonance  In ethane and ethene the electrons are localised. In some substances, the molecular orbitals extend over three or more atoms, allowing the electrons free 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 are neither double nor single bonds. They are somewhere in between. Making up a composite structure from several different structures is called mesomerism. The composite structure is called a resonance hybrid.  Resonance  Resonance is the delocalization of electrons across multiple atoms in a molecule or ion, where it can be represented by two or more resonance structures. The true structure is a resonance hybrid, which is a combination of these forms and more stable due to the spread of electron density.  Resonance in Benzene File:Benzene resonance structures.png File:Benzene resonance structures.png http://1.bp.blogspot.com/-wmQS0sbHK3s/TWa7Xeg5OxI/AAAAAAAAABE/Ff7ipy7suw8/s1600/750px-Benzene_Orbitals.svg.png  Compounds such as benzene, which have this delocalised electron ring structure are called aryl compounds. Carbon atoms are able to form a few types of covalent bonds with other carbon atoms or atoms of other elements:  Single bonds: C-C, C-H, C-O, C-X (X = halogens)  Double bonds: C=C, C=O  Triple bonds: C≡ C, C≡N  Organic compounds can be classified as unbranched, branched or ring compounds.  Straight (unbranched) Chain Compounds  Straight-chain molecules http://t0.gstatic.com/images?q=tbn:ANd9GcR5-wA1jH2oaQzTIv1pHR1TkU5YhCidwYQ6jblHTbARe0ezWm5x that are unbranched may contain single, double or triple bonds. E.g.: Branched- Chain Compounds  Branched chain compounds http://t1.gstatic.com/images?q=tbn:ANd9GcQP4xx525jjmSfGeiFjtWyMXDvWy2Os8HU5s5eq10zKFKEl7PZVLA consist Single of bond one or moreDouble bonds carbons of a straight chain compound forming bonds with more than two carbons. Triple bonds  Ring Chain Compounds Ring chain compounds consist of a ring of carbon atoms  Key Points  A large number of carbon compounds are formed by catenation- the joining of carbon atoms together to form straight or branched chains of atoms or ring compounds.  Most organic compounds are stable because of the high value of the C-C bond energy and the non-polar nature of this bond.  Hybridisation of s and p orbitals results in the formation of an orbital with mixed character.  Resonance is where the structure of a compound is a single form which is “in-between” two or more structures.  Homework Compare the examples of displayed & condensed structural formula of propane and ethanol.  Explain the characteristic of compounds which belongs to the same homologous series.