Intro to organics

Question 1

what is organic chemistry

Answer 1

study of compounds containing carbon

Question 2

what is molecular formula

Answer 2

actual number of atoms in each element in one molecule

Question 3

empirical formula

Answer 3

simplest ratio of atoms of each element in a compound

Question 4

general formula

Answer 4

number of atoms of each element when carbon is n
alkane = CnH2n+2
alkene = CnH2n

Question 5

structural formula

Answer 5

shows how atoms are joined together in a molecule

Question 6

displayed formula

Answer 6

shows all the bonds in a molecule

Question 7

skeletal formula

Answer 7

uses lines to represent bonds
the peaks are the carbon atoms
H-H bonds not usually shown

Question 8

functional group

Answer 8

atom/group of atoms responsible for chemical reactions of a molecule

Question 9

homologous series

Answer 9

family of compounds that have the same general formula and chemical properties

Question 10

rules of nomenclature

Answer 10

Systematic nomenclature can be used to name organic compounds and therefore make it easier to refer to them
The alkanes provide the basis of the naming system and the stem of each name indicates how many carbon atoms are in the longest chain in one molecule of the compound
If there are any side-chains or functional groups present, then the position of these groups is indicated by numbering the carbon atoms in the longest chain starting at the end that gives the lowest possible numbers in the name
The hydrocarbon side-chain is shown in brackets in the structural formula
CH3CH(CH3)CH2CH3

The side-chain is named by adding ‘-yl’ to the normal alkane stem
This type of group is called an alkyl group
If there are more than one of the same alkyl side-chain or functional groups, di- (for two), tri- (for three) or tetra- (for four) is added in front of its name
The adjacent numbers have a comma between them
Numbers are separated from words by a hyphen
If there is more than one type of alkyl side-chain, they are listed in alphabetic order eg 3-bromo-2-fluoro-2-methlypentane

Question 11

what rule to watch out for in alkene nomenclature

Answer 11

the bond position comes before the added molecules
so start naming from the double bond- class double bond as one

Question 12

rules of skeletal formula

Answer 12

carbon represented by end points of lines
dont draw hydrogen UNLESS they are in a separate functional group eg OH
double bonds represented by a double line adjacent to the position of carbon that it is on
if halogen present then write the actual symbol alongside the line

Question 13

what are some of the functional groups

Answer 13

alkenes- c=c-ene
alkane c-c -ane
alcohol c-OH -suffix -ol
-prefix hydroxy-
haloalkanes c-halogen prefix chloro,bromo,iodo
alehydes c=o-h suffix al
ketones c=o suffix -one
prefix oxo-
carboxylic acid c=o-oh -oic acid
nitriles c triple bond n nitrile
amines c-NH2 suffix -amine
prefix amino-

Question 14

what is isomerism

Answer 14

Isomerism is when more than one compounds have the same chemical formula but different chemical structures.

Question 15

what are the 3 types of organic molecules

Answer 15

Straight, branched and cyclic organic molecules are also called aliphatic compounds as long as they do not contain a benzene ring
Straight-chain
Straight-chain organic molecules are those in which the carbon atoms are connected to each other in one continuous chain
Branched
Branched organic molecules have side groups attached to the main chain of carbon atoms
Cyclic
Cyclic organic molecules are those in which the carbon atoms are connected to each other in a ring shape

Question 16

what are structural isomers

Answer 16

Structural isomers are compounds that have the same molecular formula but different structural formulae

Question 17

what are the 3 types of structural isomer

Answer 17

There are three different types of structural isomerism:
Chain isomerism
Positional isomerism
Functional group isomerism

Question 18

what is chain isomerism

Answer 18

Chain isomerism
Chain isomerism is when compounds have the same molecular formula, but their longest hydrocarbon chain is not the same
This is caused by branching
E.g. pentane and 2,2-dimethylpropane

Question 19

what is positional isomerism

Answer 19

Positional isomerism
Positional isomers arise from differences in the position of a functional group in each isomer
The functional group can be located on different carbons
For example, butan-1-ol and butan-2-ol

Question 20

what is functional isomerism

Answer 20

Functional group isomerism
When different functional groups result in the same molecular formula, functional group isomers arise
The isomers have very different chemical properties as they have different functional groups
For example, butanol and ethoxyethane

Question 21

how do you deduce a structural isomer

Answer 21

Step 1: Draw the structural formula of the compound
Step 2: Determine whether it is a stereo or structural isomer
Step 3: Determine whether it is a functional group, chain or positional isomerism

Draw the longest chain described in the name of the compound. Refer back to chapter 72 if you do not remember the different stems used to name carbon compounds of different chain lengths.
Number the carbons. The main chain will be numbered in such a way the substituents are given the lowest number as possible.
Add the functional groups to the carbons described in the name. The carbon to which the functional group is bonded to will be indicated with a number in the name.

Question 22

How many isomers are there of the compound with molecular formula C4H10?

Answer 22

Step 1: Draw the structural formula of the compound
Step 2: Determine whether it is a stereo or structural isomer.
There is no restricted bond rotation around the C-C bond so it is structural isomerism
Step 3: Determine whether it is a functional group, chain or positional isomerism
Functional group? No, as there are no functional groups
Positional? No, as there are no functional groups which can be positioned on different carbon atoms
Chain? Yes!

Question 23

How many isomers are there of dibromopropane, C3H6Br2?

Answer 23

Step 1: Draw the structural formula of the compound
Step 2: Determine whether it is a stereo or structural isomer
There is no restricted bond rotation around the C-C bond, so it is structural isomerism
Step 3: Determine whether it is a functional group, chain or positional isomerism
Functional group? No, as Br is the only functional group possible
Chain? No, as the longest chain can only be 3
Positional? Yes, as the two bromine atoms can be bonded to different carbon atom
that means move the functional group to all its possible positions