Intoduction To Organic Chemistry

Question 1

What is sp³ hybridisation

Answer 1

• in each of the two carbon atoms, four valence orbitals are mixed and four identical sp³ orbitals are formed

Question 2

What is sp² hybridisation

Answer 2

• in each of the two carbon atoms, three orbitals are mixed and three identical sp² hybrid orbitals are formed

Question 3

What are C-C bonds in graphite stronger than those in diamond

Answer 3

• carbon in graphite. Is sp² hybridisation while the one in diamond is sp³ hybridised
• greater s character in hybrid orbital used to form bond which leads to
• more effective overlap of orbitals and stronger bond formed with shorter bond length

Question 4

Why does greater s character lead to stronger bond

Answer 4

• electrons in s orbitals are led more closely to the nucleus than electrons in p orbital
• hybrid orbital that has more s character will have its electrons held more closely to the nucleus
• stronger attraction compared to that has less s character

Question 5

Number of C atoms and the name(Parent)

Answer 5

• meth, eth, prop, but, pent, hex, hept, oct, non, dec

Question 6

What is constitutional isomerism

Answer 6

• compounds with same molecular formula but different structural formula

Question 7

What are the types of constitutional isomerism

Answer 7

• chain isomerism
• positional isomerism
• functional group isomerism

Question 8

What is stereoisomerism

Answer 8

• differ in the way atoms are arranged in 3-dimensional space

Question 9

Types of stereoisomerism and their conditions

Answer 9

• cis-trans isomerism
  — prescence of carbon double bond to prevent rotation about the double bond
  — two different groups attached to each C atom of the double bond
  — higher atomic mass receives higher priorities
• enantiomerism
  — has a chiral carbon
  — no internal plane of symmetry

Question 10

What is optical activity

Answer 10

• ability of a substance to rotate the plane of a plane-polarised light

Question 11

What are enantiomers and their similarities and differences

Answer 11

• two molecules that are non-superimposable mirror images of each other
• identical physical properties, but rotate plane polarised light to the same extent in opposite direction
• identical chemical propertie, except in their interactions with another chiral molecule

Question 12

Counting total number of stereoisomers

Answer 12

• 2ⁿ, n= number of chiral carbon + number of carbon-carbon double bond

Question 13

What is a racemic mixture

Answer 13

• mixture with equal amounts of the two enantiomers is called a racemic mixture

Question 14

What is a meso compound

Answer 14

• compounds that are achiral but yet contain chiral centres
• the plane of symmetry makes one half of the molecule a mirror image of the other half