Introduction to organic chemistry

-carbon can form rings and very long chains which may be branched because:

• carbon can form 4 covalent bonds as 4 outer shell electrons
• C-C bonds are very strong and non- polar 
• C-H bond also strong and relatively non-polar- hydrocarbons form the skeleton of most organic compounds

Bonding in carbon compounds:

- always forms 4 covalent bonds and has 8 electrons in outer shell. does this by:

• four single bonds (C-C) like methane
• 2 single bonds and one double bond- ethene 
• one single bond and one triple bond like ethyne 

Empirical: simplest whole number ratio of atoms of each element present in a compound 

Molecular: shows the actual number of atoms of each element in the molecule- found by:

• empirical formula 
• molecular mass of empirical formula 
• molecular mass of molecule 

Displayed: shows every atom and every bond in the molecule

Structural: doesnt show all bonds and each C is written seperately with the atoms or groups attached to it 

Skeletal: straight lines represent C-C bonds. each C is assumed to form 4 bonds 

Curly Arrows: movement of a pair of electrons 

- as electrons are -vely charged, they move from high electron density areas to more positively charged areas, eg a lone pair could be attracted to the +ve end of a polar bond. 

- arrow starts at lone pair or covalent bond and moves towards the +vely charged area of a molecule to form a new bond 

Free Radicals:

- sometimes a covalent bond (shared pair of electrons) may break in a way that one electron goes to each atom that originally formed the bond. These fragments of the original molecule have an unpaired electron and are usually extremely reactive. 

Roots: the longest unbranched hydrocarbon chain- meth, eth, prop, but, pent, hex 

prefixes and suffixes: describe the changes that have been made to the molecule 

prefix: methyl, ethyl...... or cyclo for a ringed compound

suffix: eg ol for alcohols 

Functional groups: a reactive group (group that governs the chemical properties of the molecule). the functional group reacts in the same way, whatever the length of the chain

alcohols: O-H

aldehyde: H-C=O

carboxylic acid: OH-C=O

Structural isomers: same molecular formula but different structural formula 

Structural isomers can have:

same functional groups attached to main chain at different points eg 1-chloropropane and 2-chloropropane. Called Positional Isomerism

functional groups can be different- eg C2H6O can represent ethanol or methoxymethane. Called Functional Group Isomerism

a different arrangement of the hydrocarbon chain eg branching. Called Chain Isomerism. 

- where two (or more) compounds have the same structural formula. they differ in the arrangement of the bonds in space 

-E-Z isomerism tells us about the positions of substituents at either side of a C=C bond. 2 substituents may either be on the same (Z) or opposite side of the bond (E)

- you look at the atomic numbers of the atoms attached to the C=C bond and you it is the relationship between the 2 highest values you're looking at. 

• -Highest values on same side- Z
• -Highest values on opposite sides- E

Both C atoms must have 2 different groups attached to it

-You can rotate about the groups on a single bond, so there are no isomers (as structural formula is the same even when rotated) but there is no rotation about a double bond, so Z- isomers and E- isomers are seperate compounds and are not easily converted from one to the other. 

a family of organic compounds with the same functional group but different carbon chain length 

- members of a H. series have a general formula. each member differs by  CH2

-the length of the chain has little effect on chemical reactivity 

-the length of the chain affects physical properties eg melting and boiling point which increase with increased chain length as IM forces increase

-branched chains reduces MP as molecules cant pack as closely together 

Aliphatic- chain molecule 

Aromatic- ring molecule with single, double and triple bonds 

Cyclic- ring molecule with only single bonds