formulas and isomerism definitions

Question 1

what is empirical formula?

Answer 1

simplest whole number of ratio of the atoms of each elements in a molecule

Question 2

what is molecular formula?

Answer 2

actual number of atoms of each element in molecule

Question 3

what is general formula?

Answer 3

algebraic formula that describes any member of a homologous series

Question 4

what is a homologous series?

Answer 4

family of organic molecules that have same general formula and functional group

• differ by -CH2
• different physical properties

Question 5

what is structural formula?

Answer 5

shows arrangement of atoms in molecule in simplified form

Question 6

what is displayed formula?

Answer 6

shows every atom and bond in molecule

Question 7

what is skeletal formula?

Answer 7

shows bonds of carbon skeleton only

Question 8

what are the two types of isomers?

Answer 8

• structural isomers

- stereoisomers

Question 9

what is a structural isomer?

Answer 9

molecule with same molecular formula but different structural formula

Question 10

what are the three types of structural isomers?

Answer 10

• chain
• position
• functional group

Question 11

what are chain isomers and their properties?

Answer 11

• different arrangement of carbon skeleton
• similar chemical properties
• different physical properties

Question 12

what are position isomers and their properties?

Answer 12

• different position of functional group
• same carbon skeleton
• similar chemical properties
• different physical properties

Question 13

what are functional group isomers and their properties

Answer 13

• different functional group
• different chemical properties
• different physical properties

Question 14

state three types of functional group isomers

Answer 14

• aldehydes/ketones
• acids/esters
• alchols/ethers

Question 15

what is a geometric isomer?

Answer 15

same molecular formula but different spatial arrangement

Question 16

what is the other type of stereoisomer?

Answer 16

optical isomerisms

Question 17

what rules are used for stating E-Z isomerism?

Answer 17

Cahn-Ingold-Prelog priority rules (CIP)

Question 18

how does CIP rules work?

Answer 18

• look at atoms attached directly to carbon on either side of double bond
• the atom with highest atomic number has higher priority
• if the both atoms attached to carbon atom on same side of double bond are the same, look at next atom in group
• if the highest priority groups are both above/below - Z isomerism
• if they are different then its E isomerism

Question 19

why do alkenes exhibit E-Z isomerism?

Answer 19

restricted rotation due to double covalen bonds so gropus on either side of bond are frozen
since structures cannot interchange easily, the atoms occupy differnt spatial arrangements