11.3 Representing the formulae of organic compounds

Question 1

What is the molecular formula

Answer 1

Shows the number and type of atoms of each element present in a molecule.
Does not show how the atoms are joined together and different molecules can have the same molecular formula
Eg. C2H6O

Question 2

What is the empirical formular

Answer 2

The simplest whole-number ratio of the atoms of each element present in a compound
Eg. Glucose molecular formula C6H12O6 but empirical formular CH2O

Question 3

What is the general formula

Answer 3

The simplest algebraic formula for any member of a homologous series

Question 4

General formula for alkanes

Answer 4

CnH(2n+2)

Question 5

General formula for alkenes

Answer 5

CnH2n

Question 6

General formula for alcohols

Answer 6

CnH(2n+1)OH

Question 7

General formula for carboxylic acids

Answer 7

CnH2nO2

Question 8

General formula for ketones

Answer 8

CnH2nO

Question 9

What is the displayed formula

Answer 9

Shows the relative positioning of all of the atoms in a molecule and the bonds between them

Question 10

What is the structural formula

Answer 10

Uses the smallest amount of detail necessary to show the arrangement of the atoms in a molecule. Shows clearly which groups are bonded together
Eg. Butane CH3CH2CH2CH3

Question 11

What is the skeletal formula

Answer 11

A simplified organic formula, you remove all of the carbon and hydrogen labels from carbon chain, and any bonds to hydrogen atoms.
A line represents a single bond, an intersection of two lines represents a carbon atom, and the end of a line represents a -CH3 group