Introduction Organic

Question 1

what is a hydrocarbon?

Answer 1

Hydrocarbon is a compound consisting of hydrogen and carbon only

Question 2

what is the difference between saturated and unsaturated?

Answer 2

Saturated: Contain single carbon-carbon bonds only Unsaturated : Contains a C=C double bond

Question 3

what does the molecular formula show?

Answer 3

Molecular formula: The formula which shows the actual number of each type of atom

Question 4

what does the empirical formula show?

Answer 4

Empirical formula: shows the simplest whole number ratio of atoms of each element in the compound

Question 5

what is the general formula?

Answer 5

General formula: algebraic formula for a homologous series e.g. CnH2n

Question 6

what does the structural formula show?

Answer 6

Structural formula shows the minimal detail that shows the arrangement of atoms in a
molecule, eg for butane: CH3CH2CH2CH3 or CH3
(CH2
)2CH3
,

Question 7

what does the displayed formula show?

Answer 7

Displayed formula: show all the covalent bonds and atoms present in a molecule

Question 8

what is the shape around a saturated hydrocarbon and what is the bond angle?

Answer 8

tetrahedral

109.5

Question 9

what is a functional group?

Answer 9

Functional group is an atom or group of atoms which when present in different molecules
causes them to have similar chemical properties

Question 10

what is a homologous series?

Answer 10

Homologous series are families of organic compounds with the same functional
group and same general formula. •They show a gradual change in physical properties (e.g. boiling point).
• Each member differs by CH2
from the last.
• same chemical properties.

Question 11

what are the orders of priority groups, highest first?

Answer 11

Carboxylic acids >aldehydes>ketones>alcohols>alkenes>halogenoalkanes

Question 12

what is the difference between an aldehyde and a ketone?

Answer 12

aldehydes have the C=O at the end whereas ketones have it elsewhere

Question 13

how is a -OH named on an aldehyde?

Answer 13

Aldehydes have a higher priority than alcohol so the –OH
group uses the hydroxy prefix
e.g. 4- hydroxybutanol

Question 14

how do you reflect 2 ketone groups in the namings? give an example

Answer 14

If two ketone groups then di is put before – one and an e is added to the stem.
e.g.
pentane-2,4-dione

Question 15

what is the name if there are carboxylic acids on both ends of the chain?

Answer 15

If there are carboxylic acid groups on both ends of the

chain then it is called a - dioic acid

Question 16

what are the 2 ways to break a covalent bond?

Answer 16

• homolytic fission

- heterolytic fission

Question 17

define homolytic fission

Answer 17

each atom gets one electron from the covalent bond- this forms 2 free radicals
- this is demonstrated using a 1 headed arrow

Question 18

define heterolytic fission

Answer 18

one atom gets both electrons- this produces an ion

-this is demonstrated using a double headed arrow

Question 19

define free radical

Answer 19

Free radicals do not have a charge and

Definition
A free radical is a reactive species
which possess an unpaired electron

Question 20

what is a structural formula? what are the 3 types they arise from?

Answer 20

Structural isomers: same molecular formula different structures (or structural formulae)
Structural isomerism can arise from
•Chain isomerism
•Position isomerism
•Functional group isomerism

Question 21

what is a chain isomer?

Answer 21

Chain isomers: Compounds with the same molecular formula but different
structures of the carbon skeleton

e. g.
- pentane, 2-methylbutane, 2,2- dimethylpropane

Question 22

what is a position isomer?

Answer 22

position isomers: Compounds with the same molecular formula but different structures due to
different positions of the same functional group on the same carbon skeleton

e. g.
- 1-bromopropane, 2-bromopropane

Question 23

what is a functional group isomer?

Answer 23

Functional group isomers: Compounds with the same molecular formula but with
atoms arranged to give different functional groups

e. g.
- ethanol(alcohol), and methoxymethane(an ether) or cyclohexane and hexene

Question 24

what is sterioisomerism?

Answer 24

Stereoisomers have the same structural formulae but

have a different spatial arrangement of atoms.

Question 25

why is there E-Z isomerism?

Answer 25

E-Z stereoisomers arise when:
(a) There is restricted rotation around the C=C double bond.
(b) There are two different groups/atoms attached both ends of the
double bond

Question 26

what is a priority group?

Answer 26

Priority Group: The atom with the bigger

atomic number is classed as the priority atom

Question 27

what are the CIP priority rules?

Answer 27

1. Compare the atomic number of the
   atoms directly attached to each side of the
   double bond; the atom of higher atomic
   number is given priority.
2. If the atoms are the same, consider the
   atoms at distance 2 from the double bond.
   Make a list of each atom bonded to the one
   directly attached to the double bond.
   Arrange list in order of decreasing atomic
   number. Compare the lists atom by atom; at
   the earliest difference, the group containing
   the atom of higher atomic number is given
   priority

Question 28

what effect does E-Z isomerism have on physical properties?

Answer 28

E-Z isomers can have different boiling points.
Z-1,2-dichloroethene
Boiling point =60oC
This molecule is polar. The polar C-Cl bonds are on
the same side of the molecule. One side of the
molecule is slightly negative.
The intermolecular forces are both van der waals
and permanent dipole-dipole attractions.

E-1,2-dichloroethene
Boiling point =48oC
This molecule is non- polar. The polar C-Cl
bonds are on opposite sides of the molecule.
The dipoles cancel out.
The intermolecular forces are only van der
waals so lower boiling point.