Organic Chemistry Intro

Question 1

state the general formula of alkanes

Answer 1

C_nH_2n+2

Question 2

state the general formula of alkenes

Answer 2

C_nH_2n

Question 3

state the general formula of alcohols

Answer 3

C_nH_2n+1OH

Question 4

state the general formula of alkynes

Answer 4

C_nH_2n-2

Question 5

state the general formula of cyclic alkanes

Answer 5

C_nH_2n

Question 6

what is molecular formula? what is the molecular formula of ethane?

Answer 6

• actual number of atoms in a molecule or element
• ethane = C₂H₆

Question 7

what is empirical formula? what is the empirical formula of ethane (C₂H₆)?

Answer 7

• simplest whole number ratio of atoms in a compound
• ethane (C₂H₆) = CH₃

Question 8

what is structural formula? what is the structural formula of butan-1-ol? (C₄H₉OH)

Answer 8

• arrangement of atoms in a molecule without showing all the bonds
• butan-1-ol (C₄H₉OH) = CH₃CH₂CH₂CH₂OH

Question 9

what is skeletal formula?

Answer 9

• shows the bonds of the carbon skeleton only
• hydrogen and carbon atoms not shown but functional groups are

Question 10

what is displayed formula?

Answer 10

• shows the arrangement of atoms showing all the bonds and atoms in the molecule

Question 11

what is a homologous series?

Answer 11

• a group of compounds with the same functional group and general formula
• successive members of the same homologous series increases by CH₂

Question 12

what is the prefix/suffix of the alkane homologous series? give an example.

Answer 12

• ane, e.g. butane

Question 13

what is the prefix/suffix of the branched alkane homologous series? give an example.

Answer 13

alkyl- -ane, e.g. methylpropane

Question 14

what is the prefix/suffix of the alkene homologous series? give an example.

Answer 14

• ene, e.g. propene

Question 15

what is the prefix/suffix of the alcohol homologous series? give an example.

Answer 15

• ol, e.g. ethanol

Question 16

what is the prefix/suffix of the aldehyde homologous series? give an example.

Answer 16

-al, e.g. propanal

Question 17

what is the prefix/suffix of the ketone homologous series? give an example.

Answer 17

-one, e.g. propanone

Question 18

what is the prefix/suffix of the carboxylic acid homologous series? give an example.

Answer 18

• oic acid, e.g. butanoic acid

Question 19

what is the prefix/suffix of the halogenoalkane homologous series? give an example.

Answer 19

fluoro-/chloro-/bromo-/iodo-
e.g. bromoethane

Question 20

what is the prefix/suffix of the cycloalkane homologous series? give an example.

Answer 20

cyclo- -ane, e.g. cyclopentane

Question 21

describe the process of naming molecules (nomenclature)

Answer 21

1) find length of stem by counting the longest continuous chain of carbons
2) make note of any alkyl groups + their prefix - if multiple write in alphabetical order
3) make note of functional group to use to find suffix/prefix
4) if more than one identical functional group or side chain present, put di/tri/tetra in front

Question 22

what is a chemical mechanism? how can they be represented?

Answer 22

• shows the movement of an electron during a chemical reaction
• curly arrows can be used to show the movement of a pair of electrons
• they always start from the area donating the electrons and end at the area accepting the electron or to the formation of a new bond

Question 23

what are structural isomers?

Answer 23

same molecular formula but different structural formula

Question 24

state the 3 types of structural isomerism

Answer 24

• chain
• positional
• functional

Question 25

what is chain isomerism?

Answer 25

same molecular formula, different arrangement of carbon skeleton

Question 26

what is positional isomerism?

Answer 26

same molecular formula, different position of the functional group on the carbon skeleton

Question 27

what is functional group isomerism?

Answer 27

same molecular formula, different functional group

Question 28

what are stereoisomers? how do they work?

Answer 28

• same structural formula different arrangement of atoms in space
• e.g. E-Z isomerism
• a single bond can rotate but a double bond cannot
• the c=c bond and the atoms bonded directly to this are flat (planar) so can’t rotate and are rigid

Question 29

when does E-Z isomerism occur? what does the E mean? what does the Z mean?

Answer 29

• when there are 2 different atoms or groups of atoms on the same carbon
• E: same groups opposite the double bond (diagonal or vertical)
• Z: same groups on the same side of the double bond

Question 30

what are the Cahn - Ingold - Prelog (CIP) rules? when are they used?

Answer 30

• used when deciding if an isomer is E or Z when there are 4 different groups around the double bond
  1) label carbons with double bond as carbon 1 and carbon 2
  2) calculate the atomic (proton) number of the first element directly bonded to carbon 1 C=C. the atom with the highest atomic number is given higher priority.
  3) repeat for carbon 2
  4) use high priority groups to determine if E or Z
  *may have to check further down the chain of priorities are the same