Unit 3: Section 1 - Introduction to Organic Chemistry

Question 1

What is the general formula?

Answer 1

An algebraic formula that can describe any member of a homologous series

Question 2

What is the empirical formula?

Answer 2

The simplest ratio of atoms of each element in a compound

Question 3

What is the molecular formula?

Answer 3

The actual number of atoms of each element in a molecule

Question 4

What is the structural formula?

Answer 4

Shows the atoms carbon by carbon with the attached hydrogens and functional groups

Question 5

What is the skeletal formula?

Answer 5

Shows the bonds of the carbon skeleton only, with any functional groups - hydrogens are assumed

Question 6

What is the displayed formula?

Answer 6

Shows how all the atoms are arranged, and the bonds between them

Question 7

What is a homologous series?

Answer 7

A group of compounds that contain the same functional group - can all be represented by the same general formula
* Same functional group therefore the same chemical propertie
* Consecutive members increase by CH2

Question 8

How to name organic ccompounds?

Answer 8

1. Count the carbons in the longest carbon chain that contains the functional group which gives you the stem
2. The main functional group of the molecule usually gives you the suffix
3. Number the carbons in the longest chain so htat the cabon with the main functional group attached has the lowest number - if there’s more than one longest chain pick the one with the most side chains
4. Any side chains or less important functional groupd are added as prefixes at the start of the stem in alphabetical order with the number of the carbon its attached to
5. If there’s more than one identical side chain or functional group use di, tri or tetra but ignore this when placing in alphabetical order

Question 9

What is the IUPAC system and why is it needed?

Answer 9

The international language of chemistry to allow scientific ideas to communicated globally more effectively so it’s easier for scientists to test each others theories

Question 10

What do curly arrows represent?

Answer 10

The arrow starts at the bond or lone pair where the electrons are at the beginning of the reaction, then it popints to where the new bon dis formed at the end of the reaction

Question 11

What are strucutral isomers?

Answer 11

Same molecular formula but different structural formula

Question 12

What are the different types of structural isomers?

Answer 12

Chain isomers - Different arrangement of the carbon skeleton
Positional isomers - Same skeleton and the same atoms or groups of atoms attached but they are attached to a different carbon
Functional group isomers - Same atoms arranged into different functional groups

Question 13

What are stereoisomers?

Answer 13

Same structural formula but a different arrangement of atoms in space

Question 14

How does E/Z isomerism arise?

Answer 14

1. Carbon atoms in a C=C double bond and the atoms bonded to these atoms are all planar
2. The double bond can’t rotate - rigid and don’t bend much either
3. THe restricted rotation is what causes the isomerism

Question 15

How doalkenes show E/Z isomerism?

Answer 15

1. Alkenes have restricted rotation around their C=C bonds
2. If there are different atoms or groups attached to them, the arrangemtn of those groups can change to create stereoisomers
3. Z- isomer - highest priority groups on the same side
   E- isomer - highest priority group poisitioned across the double bond

Question 16

How do you use Cahn-Ingold-Prelog Priority Rules?

Answer 16

1. Assign a priority to the 2 atoms attached to each carbon in the double bond
2. Look at the atoms bonded to each of the C=C carbon atoms, the atom with the highest atomic number on each carbon is given priority - if the same go further down the chain
3. To work out the isomer work out how the higher priority groups are arranged
   CAREFUL - this can mean that if the same groups are the same side, it isn’t z isomerism