3.1 Intro To Organic Chemistry

Question 1

What’s a general formula

Answer 1

An algebraic formula that can describe any member of a family of compounds
Eg, CnH2n+1OH for all alcohols

Question 2

What’s an empirical formula

Answer 2

The simplest ratio of atoms of each element in a compound
Ethan C2H6 would be CH3

Question 3

Molecular formula; what is it

Answer 3

The actual number of atoms of each element in a molecule
C4H10O

Question 4

What is a Structural formula

Answer 4

Shows the atoms carbon by carbon, dividing up the molecule
With attached H and functional groups

CH3CH2CH2CH2OH

Question 5

What’s the skeletal formula

Answer 5

Shows the bonds of the carbon skeleton only, with any functional groups
The hydrogen and carbon atoms aren’t shown

Any vertices or line ends are a carbon (hydrogens around aren’t shown)

Question 6

What’s the displayed formula

Answer 6

Shows how all the atoms are arranged
And all the bonds between

H — C — H etc

Question 7

What’s a homologous series

Answer 7

—> a group of compounds that contain the same functional group
(a reactive part of molecule, gives most of its chemical properties)
- can all be represented using the same general formula

You can use a general formula to work out the molecular formula
If any member of a homologous series
- each successive member of a homologous series differs by a CH2 group

MAIN HOMOLOGOUS SERIES TO KNOW..
DIAGRAM NO.1

Question 8

What is nomenclature

Answer 8

It’s the naming of organic compounds
- name any carbon compound using these rules..

1. Count the carbons in the longest continuous chain that contains the functional group
   —> the stem = meth, eth, prop, but, pent, hex..
2. The main functional group of the molecule gives the suffix
   (Eg. If OH is the main functional group, it will end in -ol) = pentanol
3. Number the Cs in the longest carbon chain
   So that the C with the main functional group
   attached has the lowest possible number.

If there’s more than one longest chain (eg, two with 5 Cs)
Pick the one with most side chains

..
4. Write the C number that the functional group is on BEFORE suffix
Eg. OH on Carbon 2 means Pentan-2-ol

5. Any side chains/less important functional groups are prefixes
   Put them in alphabetical order with the number C atom it’s attached to
6. If there’s multiple identical side chain / functional group
   Use di, tri, or tetra before that part of the name
   —> ignore this while working out the alphabetical order

Eg. diagram no.2
PRACRICE IN BOOKLET

Question 9

What are the homologous series at AS and their functional groups? (x8)

Answer 9

diagram no.3

Question 10

What are (structural) isomers

Answer 10

They’re compounds with same molecular formula but a different structural formula
Eg. C5H12 can have three possible isomers : can be pentane, 2methylbutane, etc

The three types of of structural isomers
Include chain, positional and functional group isomers

Question 11

What’s chain isomerism

Answer 11

When there’s more than one way of arranging Carbon atoms in longest chain
Eg. C5H12 exists as three chain isomers

Question 12

What’s positional isomerism

Answer 12

Positional isomers have same carbon chain and same functional group but
The functional group is attached at different points along carbon chain
—> it is moved along carbon chain

Question 13

What’s functional group isomerism

Answer 13

Functional group isomers are compounds with same molecular formula
That have different functional groups.

Eg. C3H6O could be an aldehyde or ketone